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A340952

Number of ways to write n as an ordered sum of 7 nonzero triangular numbers.

1, 0, 7, 0, 21, 7, 35, 42, 35, 112, 42, 182, 112, 210, 260, 217, 462, 252, 651, 399, 728, 777, 672, 1232, 749, 1533, 1127, 1659, 1617, 1792, 2289, 1890, 2926, 2212, 3339, 2990, 3584, 3654, 4046, 4613, 4263, 5754, 4487, 6636, 5733, 6825, 7014, 7203, 8617, 7560, 10087, 8302

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OFFSET

7,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..10000

FORMULA

G.f.: (theta_2(sqrt(x)) / (2 * x^(1/8)) - 1)^7, where theta_2() is the Jacobi theta function.

MAPLE

b:= proc(n, k) option remember; local r, t, d; r, t, d:= $0..2;

if n=0 then `if`(k=0, 1, 0) else

while t<=n do r:= r+b(n-t, k-1); t, d:= t+d, d+1 od; r fi

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