OFFSET
1,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: Sum_{k>0} binomial(k+3,5) * (-x)^k/(1 - x^k).
a(n) = Sum_{d|n} (-1)^d * binomial(d+3,5).
MATHEMATICA
a[n_] := DivisorSum[n, (-1)^#*Binomial[# + 3, 5] &]; Array[a, 40] (* Amiram Eldar, Jul 18 2023 *)
PROG
(PARI) my(N=50, x='x+O('x^N)); concat(0, Vec(sum(k=1, N, x^(2*k)/(1+x^k)^6)))
(PARI) a(n) = sumdiv(n, d, (-1)^d*binomial(d+3, 5));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jun 11 2023
STATUS
approved