Primes and Squares











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Place a different prime or square number on each of the fifteen disks below so that the number in any disk that lies on two others is the sum of the numbers in those disks. Do so in such a way that the number on the apex is as small as possible.



enter image description here










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  • is this something you composed yourself?
    – Kate Gregory
    15 hours ago










  • @KateGregory: A variation on an old theme.
    – Bernardo Recamán Santos
    15 hours ago










  • Zero (as a square) allowed?
    – z100
    10 hours ago










  • @z100 You could not use a zero, since $x + 0 = x$, and therefore you'd have to have two $x$'es in your grid; that is disallowed. See imgur.com/a/gPWWkaN for explanation.
    – Hugh
    9 hours ago

















up vote
7
down vote

favorite












Place a different prime or square number on each of the fifteen disks below so that the number in any disk that lies on two others is the sum of the numbers in those disks. Do so in such a way that the number on the apex is as small as possible.



enter image description here










share|improve this question






















  • is this something you composed yourself?
    – Kate Gregory
    15 hours ago










  • @KateGregory: A variation on an old theme.
    – Bernardo Recamán Santos
    15 hours ago










  • Zero (as a square) allowed?
    – z100
    10 hours ago










  • @z100 You could not use a zero, since $x + 0 = x$, and therefore you'd have to have two $x$'es in your grid; that is disallowed. See imgur.com/a/gPWWkaN for explanation.
    – Hugh
    9 hours ago















up vote
7
down vote

favorite









up vote
7
down vote

favorite











Place a different prime or square number on each of the fifteen disks below so that the number in any disk that lies on two others is the sum of the numbers in those disks. Do so in such a way that the number on the apex is as small as possible.



enter image description here










share|improve this question













Place a different prime or square number on each of the fifteen disks below so that the number in any disk that lies on two others is the sum of the numbers in those disks. Do so in such a way that the number on the apex is as small as possible.



enter image description here







mathematics arithmetic






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share|improve this question











share|improve this question




share|improve this question










asked 16 hours ago









Bernardo Recamán Santos

2,1211138




2,1211138












  • is this something you composed yourself?
    – Kate Gregory
    15 hours ago










  • @KateGregory: A variation on an old theme.
    – Bernardo Recamán Santos
    15 hours ago










  • Zero (as a square) allowed?
    – z100
    10 hours ago










  • @z100 You could not use a zero, since $x + 0 = x$, and therefore you'd have to have two $x$'es in your grid; that is disallowed. See imgur.com/a/gPWWkaN for explanation.
    – Hugh
    9 hours ago




















  • is this something you composed yourself?
    – Kate Gregory
    15 hours ago










  • @KateGregory: A variation on an old theme.
    – Bernardo Recamán Santos
    15 hours ago










  • Zero (as a square) allowed?
    – z100
    10 hours ago










  • @z100 You could not use a zero, since $x + 0 = x$, and therefore you'd have to have two $x$'es in your grid; that is disallowed. See imgur.com/a/gPWWkaN for explanation.
    – Hugh
    9 hours ago


















is this something you composed yourself?
– Kate Gregory
15 hours ago




is this something you composed yourself?
– Kate Gregory
15 hours ago












@KateGregory: A variation on an old theme.
– Bernardo Recamán Santos
15 hours ago




@KateGregory: A variation on an old theme.
– Bernardo Recamán Santos
15 hours ago












Zero (as a square) allowed?
– z100
10 hours ago




Zero (as a square) allowed?
– z100
10 hours ago












@z100 You could not use a zero, since $x + 0 = x$, and therefore you'd have to have two $x$'es in your grid; that is disallowed. See imgur.com/a/gPWWkaN for explanation.
– Hugh
9 hours ago






@z100 You could not use a zero, since $x + 0 = x$, and therefore you'd have to have two $x$'es in your grid; that is disallowed. See imgur.com/a/gPWWkaN for explanation.
– Hugh
9 hours ago












2 Answers
2






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up vote
8
down vote



accepted










A much lower upper bound, which I'm fairly sure is optimal (assuming 0 is disallowed).





              1669 
576 || 1093
383 || 193 || 900
347 || 36 || 157 || 743
324 || 23 || 13 || 144 || 599






share|improve this answer










New contributor




B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.


















  • Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
    – z100
    9 hours ago












  • @z100 I'm afraid I'm not sure what you're asking - could you clarify?
    – B. Mehta
    9 hours ago










  • My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
    – benj2240
    6 hours ago


















up vote
5
down vote













Alright, I’ve definitely got an upper bound here.




enter image description here




In text:





                  390625 
140625 || 250000
50625 || 90000 || 160000
18225 || 32400 || 57600 || 102400
6561 || 11664 || 20736 || 36864 || 65536



However,




this uses all square numbers, and is far from optimal. I’ll have to see if I can reduce it by using primes.







share|improve this answer























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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    8
    down vote



    accepted










    A much lower upper bound, which I'm fairly sure is optimal (assuming 0 is disallowed).





                  1669 
    576 || 1093
    383 || 193 || 900
    347 || 36 || 157 || 743
    324 || 23 || 13 || 144 || 599






    share|improve this answer










    New contributor




    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.


















    • Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
      – z100
      9 hours ago












    • @z100 I'm afraid I'm not sure what you're asking - could you clarify?
      – B. Mehta
      9 hours ago










    • My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
      – benj2240
      6 hours ago















    up vote
    8
    down vote



    accepted










    A much lower upper bound, which I'm fairly sure is optimal (assuming 0 is disallowed).





                  1669 
    576 || 1093
    383 || 193 || 900
    347 || 36 || 157 || 743
    324 || 23 || 13 || 144 || 599






    share|improve this answer










    New contributor




    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.


















    • Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
      – z100
      9 hours ago












    • @z100 I'm afraid I'm not sure what you're asking - could you clarify?
      – B. Mehta
      9 hours ago










    • My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
      – benj2240
      6 hours ago













    up vote
    8
    down vote



    accepted







    up vote
    8
    down vote



    accepted






    A much lower upper bound, which I'm fairly sure is optimal (assuming 0 is disallowed).





                  1669 
    576 || 1093
    383 || 193 || 900
    347 || 36 || 157 || 743
    324 || 23 || 13 || 144 || 599






    share|improve this answer










    New contributor




    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    A much lower upper bound, which I'm fairly sure is optimal (assuming 0 is disallowed).





                  1669 
    576 || 1093
    383 || 193 || 900
    347 || 36 || 157 || 743
    324 || 23 || 13 || 144 || 599







    share|improve this answer










    New contributor




    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    share|improve this answer



    share|improve this answer








    edited 9 hours ago





















    New contributor




    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.









    answered 10 hours ago









    B. Mehta

    1963




    1963




    New contributor




    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.





    New contributor





    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    B. Mehta is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.












    • Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
      – z100
      9 hours ago












    • @z100 I'm afraid I'm not sure what you're asking - could you clarify?
      – B. Mehta
      9 hours ago










    • My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
      – benj2240
      6 hours ago


















    • Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
      – z100
      9 hours ago












    • @z100 I'm afraid I'm not sure what you're asking - could you clarify?
      – B. Mehta
      9 hours ago










    • My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
      – benj2240
      6 hours ago
















    Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
    – z100
    9 hours ago






    Algorithm used extening the order? E.G.: 1st order: 1 ; 2nd order: 3 (1 2) ; 3rd order: 16 (3 13) (1 2 11) ; or 16 (13 3) (12 1 2) ;
    – z100
    9 hours ago














    @z100 I'm afraid I'm not sure what you're asking - could you clarify?
    – B. Mehta
    9 hours ago




    @z100 I'm afraid I'm not sure what you're asking - could you clarify?
    – B. Mehta
    9 hours ago












    My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
    – benj2240
    6 hours ago




    My own (extremely shameful, dirty, brute-force) code confirms this answer is optimal. I can also provide the smallest apex value for a 4-level tree, which is 23.
    – benj2240
    6 hours ago










    up vote
    5
    down vote













    Alright, I’ve definitely got an upper bound here.




    enter image description here




    In text:





                      390625 
    140625 || 250000
    50625 || 90000 || 160000
    18225 || 32400 || 57600 || 102400
    6561 || 11664 || 20736 || 36864 || 65536



    However,




    this uses all square numbers, and is far from optimal. I’ll have to see if I can reduce it by using primes.







    share|improve this answer



























      up vote
      5
      down vote













      Alright, I’ve definitely got an upper bound here.




      enter image description here




      In text:





                        390625 
      140625 || 250000
      50625 || 90000 || 160000
      18225 || 32400 || 57600 || 102400
      6561 || 11664 || 20736 || 36864 || 65536



      However,




      this uses all square numbers, and is far from optimal. I’ll have to see if I can reduce it by using primes.







      share|improve this answer

























        up vote
        5
        down vote










        up vote
        5
        down vote









        Alright, I’ve definitely got an upper bound here.




        enter image description here




        In text:





                          390625 
        140625 || 250000
        50625 || 90000 || 160000
        18225 || 32400 || 57600 || 102400
        6561 || 11664 || 20736 || 36864 || 65536



        However,




        this uses all square numbers, and is far from optimal. I’ll have to see if I can reduce it by using primes.







        share|improve this answer














        Alright, I’ve definitely got an upper bound here.




        enter image description here




        In text:





                          390625 
        140625 || 250000
        50625 || 90000 || 160000
        18225 || 32400 || 57600 || 102400
        6561 || 11664 || 20736 || 36864 || 65536



        However,




        this uses all square numbers, and is far from optimal. I’ll have to see if I can reduce it by using primes.








        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited 14 hours ago









        gabbo1092

        4,581735




        4,581735










        answered 14 hours ago









        Excited Raichu

        4,283752




        4,283752






























             

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