OFFSET
1,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..450
FORMULA
a(n) = (n-1)! * A048272(n).
MATHEMATICA
a[n_] := (n - 1)! * DivisorSum[n, (-1)^(# + 1) &]; Array[a, 25] (* Amiram Eldar, Apr 28 2021 *)
PROG
(PARI) N=40; x='x+O('x^N); Vec(serlaplace(log(prod(k=1, N, (1+x^k)^(1/k)))))
(PARI) {a(n) = if(n<1, 0, (n-1)!*sumdiv(n, d, (-1)^(d+1)))}
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Nov 10 2020
STATUS
approved