OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..445
FORMULA
E.g.f.: Sum_{k>0} (-x)^k/(k!*(x^k-1)) or Sum_{k>0}(1-exp(-x^k)).
MATHEMATICA
f[n_] := Block[{d = Divisors@n}, Plus @@ (n!*(-1)^(d + 1)/d!)]; Array[f, 19] (* or *) (* Robert G. Wilson v, Sep 13 2007 *)
Rest[ Range[0, 20]! CoefficientList[ Series[ Sum[(-x)^k/(k!*(x^k - 1)), {k, 25}], {x, 0, 20}], x]] (* or *) (* Robert G. Wilson v, Sep 13 2007 *)
Rest[ Range[0, 20]! CoefficientList[ Series[ Sum[1 - Exp[ -x^k], {k, 25}], {x, 0, 20}], x]] (* Robert G. Wilson v, Sep 13 2007 *)
PROG
(PARI) a(n) = n!*sumdiv(n, d, (-1)^(d+1)/d!); \\ Michel Marcus, Sep 29 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Sep 06 2007
EXTENSIONS
More terms from Robert G. Wilson v, Sep 13 2007
STATUS
approved