A281870 Number of sets of exactly ten positive integers <= n having a square element sum.

0, 1, 5, 16, 58, 171, 434, 1030, 2259, 4645, 9071, 16927, 30354, 52586, 88351, 144425, 230347, 359329, 549338, 824505, 1216843, 1768278, 2533124, 3581117, 5000891, 6904149, 9430598, 12753622, 17086885, 22692075, 29887626, 39058827, 50669397, 65274492, 83535475

Offset

10,3

Links

Alois P. Heinz, Table of n, a(n) for n = 10..1000

Example

a(11) = 1: {1,3,4,5,6,7,8,9,10,11}.
a(12) = 5: {1,2,3,4,5,7,9,10,11,12}, {1,2,3,4,6,7,8,10,11,12}, {1,2,3,5,6,7,8,9,11,12}, {1,2,4,5,6,7,8,9,10,12}, {1,3,4,5,6,7,8,9,10,11}.

Maple

b:= proc(n, i, t) option remember;
      `if`(i<t, 0, `if`(n=0, `if`(t=0, 1, 0),
      `if`(t<1 or n<t*(t+1)/2 or n>(t+1)*(2*i-t)/2, 0,
      `if`(i>n, 0, b(n-i, i-1, t-1))+b(n, i-1, t))))
    end:
a:= proc(n) option remember; `if`(n<0, 0, a(n-1)+add(
       b(j^2-n, n-1, 9), j=isqrt(n-45)..isqrt(10*n-45)))
    end:
seq(a(n), n=10..60);

Crossrefs

Column k=10 of A281871.

Sequence in context: A057553 A226973 A006217 * A116914 A047103 A226897

Adjacent sequences: A281867 A281868 A281869 * A281871 A281872 A281873

Keyword

nonn

Author

Alois P. Heinz, Feb 01 2017

Status

approved