OFFSET
0,4
FORMULA
PROG
(PARI) seq(n) = my(A=1); for(i=1, n, A=exp(sum(k=1, i, subst(A, x, x^k)*x^k/(k*(1+3*x^k)))+x*O(x^n))); Vec(A);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jun 10 2023
STATUS
approved