OFFSET
0,3
FORMULA
G.f.: Product_{k>0} (1-x^(7*k))^2 * (1-x^(7*k-3)) * (1-x^(7*k-4)) / ((1-x^(7*k-2)) * (1-x^(7*k-5)))^2.
PROG
(PARI) my(N=110, x='x+O('x^N)); Vec(sum(k=-N, N, x^(2*k)/(1-x^(7*k+2))))
(PARI) my(N=110, x='x+O('x^N)); Vec(prod(k=1, N, (1-x^(7*k))^2*(1-x^(7*k-3))*(1-x^(7*k-4))/((1-x^(7*k-2))*(1-x^(7*k-5)))^2))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Aug 01 2024
STATUS
approved