OFFSET
1,2
LINKS
Winston de Greef, Table of n, a(n) for n = 1..1500
FORMULA
G.f.: -(1/(1 - x)) * Sum_{j>=1} Sum{k>=1} (-k)^j * x^(k*(2*j-1)) * (1 - x^(2*j-1)).
MATHEMATICA
a[n_] := Sum[(-1)^(k + 1) * Floor[n/(2*k - 1)]^k, {k, 1, n}]; Array[a, 50] (* Amiram Eldar, Dec 18 2021 *)
PROG
(PARI) a(n) = sum(k=1, n, (-1)^(k+1)*(n\(2*k-1))^k);
(PARI) my(N=66, x='x+O('x^N)); Vec(-sum(j=1, N, (1-x^(2*j-1))*sum(k=1, N, (-k)^j*x^(k*(2*j-1))))/(1-x))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Dec 18 2021
STATUS
approved