OFFSET
1,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..449
MATHEMATICA
nmax = 30; A000593 = Table[Sum[Mod[d, 2] d, {d, Divisors[n]}], {n, 1, nmax}]; Table[n!/2 * Sum[A000593[[k]] * A000593[[n-k]] / k / (n-k), {k, 1, n-1}], {n, 1, nmax}] (* Vaclav Kotesovec, Nov 09 2020 *)
PROG
(PARI) {a(n) = my(t='t); n!*polcoef(polcoef(prod(k=1, n, (1+x^k+x*O(x^n))^t), n), 2)}
(PARI) sod(n) = sigma(n>>valuation(n, 2)); \\ A000593
a(n) = (n!/2) * sum(k=1, n-1, sod(k)*sod(n-k)/(k*(n-k))); \\ Michel Marcus, Nov 09 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 09 2020
STATUS
approved