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A281870
Number of sets of exactly ten positive integers <= n having a square element sum.
2
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
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
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 01 2017
STATUS
approved