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%I #14 Jun 22 2023 07:20:26
%S 1,-3,6,-10,12,-9,-2,24,-54,80,-84,42,66,-234,420,-536,450,-39,-740,
%T 1770,-2688,2898,-1722,-1320,6078,-11349,14736,-12992,3084,15999,
%U -41212,64032,-70788,46020,20778,-126132,244120,-323421,295410,-96848,-293868,815829,-1297972
%N Expansion of 1/(Sum_{k>=0} x^(k^2))^3.
%F a(0) = 1; a(n) = -(3/n) * Sum_{k=1..n} A162552(k) * a(n-k).
%o (PARI) my(N=50, x='x+O('x^N)); Vec(1/sum(k=0, sqrtint(N), x^k^2)^3)
%Y Convolution inverse of A002102.
%Y Column k=3 of A363778.
%Y Cf. A162552.
%K sign,easy
%O 0,2
%A _Seiichi Manyama_, Jun 21 2023