OFFSET
0,2
FORMULA
a(0) = 1; a(n) = -(2/n) * Sum_{k=1..n} A162552(k) * a(n-k).
PROG
(PARI) my(N=50, x='x+O('x^N)); Vec(1/sum(k=0, sqrtint(N), x^k^2)^2)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Seiichi Manyama, Jun 21 2023
STATUS
approved