A368688 Expansion of g.f. Sum_{n>=1} q^n/(1-q^n-q^(3*n)).

1, 2, 2, 4, 4, 7, 7, 13, 15, 24, 29, 50, 61, 96, 134, 202, 278, 426, 596, 898, 1286, 1903, 2746, 4082, 5900, 8703, 12679, 18658, 27202, 40023, 58426, 85828, 125521, 184195, 269552, 395502, 578950, 849088, 1243586, 1823380, 2670965, 3915867, 5736962, 8409830, 12322560, 18062121, 26467300, 38793983, 56849093

Offset: 1

Author

Joerg Arndt, Jan 03 2024

Keywords

• nonn

Crossrefs

Cf. A007435 (g.f. Sum{n>=1} q^n/(1-q^n-q^(2*n))), A368689 (g.f. Sum_{n>=1} q^n/(1-q^(2*n)-q^(3*n))), A368687 (g.f. Sum_{n>=1} q^n/(1-q^n-q^(2*n)-q^(3*n))).

Programs

PARI

my(N=55, q='q+O('q^N)); Vec(sum(n=1,N,q^n/(1-q^n-q^(3*n))))