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A281869 Number of sets of exactly nine positive integers <= n having a square element sum. 2
0, 1, 3, 14, 47, 121, 296, 660, 1358, 2646, 4905, 8704, 14887, 24649, 39651, 62175, 95286, 143038, 210732, 305210, 435195, 611697, 848494, 1162662, 1575195, 2111713, 2803273, 3687272, 4808464, 6220104, 7985229, 10178073, 12885638, 16209468, 20267579, 25196567 (list; graph; refs; listen; history; text; internal format)
OFFSET

9,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 9..1000

EXAMPLE

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

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

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, 8), j=isqrt(n-36)..isqrt(9*n-36)))

    end:

seq(a(n), n=9..60);

CROSSREFS

Column k=9 of A281871.

Sequence in context: A027953 A264501 A104196 * A202144 A287426 A246149

Adjacent sequences:  A281866 A281867 A281868 * A281870 A281871 A281872

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Feb 01 2017

STATUS

approved

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Last modified February 22 10:29 EST 2019. Contains 320395 sequences. (Running on oeis4.)