OFFSET
0
FORMULA
G.f.: Sum_{k in Z} (-1)^k * x^(k * (7*k + 1) / 2).
a(0) = 1; a(n) = -(1/n) * Sum_{k=1..n} A363804(k) * a(n-k).
PROG
(PARI) my(N=100, x='x+O('x^N)); Vec(prod(k=1, N, 1-[1, 0, 0, 1, 1, 0, 0][k%7+1]*x^k))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jun 23 2023
STATUS
approved