A319243 - OEIS

%I #9 Sep 16 2018 16:35:52

%S 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,

%T 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,

%U -14,4,2,-16,18,-2,-10,24,-30,14,4,-20,34,-26,2,16,-30,26,2,-20

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

%F Convolution inverse of A103265.

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

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

%Y Cf. A103265.

%K sign

%O 0,2

%A _Seiichi Manyama_, Sep 15 2018