A319243 - OEIS

A319243

Expansion of Product_{k>0} (1 - x^(k^2))/(1 + x^(k^2)).

1, -2, 2, -2, 0, 2, -2, 2, 0, -4, 6, -6, 4, 2, -6, 6, -6, 2, 4, -6, 8, -6, -2, 6, -8, 8, -2, -4, 8, -10, 6, 2, -6, 6, -2, -6, 8, -6, 2, 6, -8, 6, -2, -6, 8, -4, -2, 10, -14, 8, 0, -6, 16, -14, 4, 2, -16, 18, -2, -10, 24, -30, 14, 4, -20, 34, -26, 2, 16, -30, 26, 2, -20

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..72.

FORMULA

Convolution inverse of A103265.

PROG

(PARI) N=99; x='x+O('x^N); Vec(prod(k=1, sqrtint(N), (1-x^(k^2))/(1+x^(k^2))))

CROSSREFS

Product_{k>0} (1 - x^(k^m))/(1 + x^(k^m)): A002448 (m=1), this sequence (m=2), A319244 (m=3).

Cf. A103265.