OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..500
FORMULA
E.g.f.: Sum_{k>0}(1-exp(-x^k/k!)).
MATHEMATICA
Rest[ Range[0, 30]! CoefficientList[ Series[ Sum[1 - Exp[ -x^k/k! ], {k, 30}], {x, 0, 30}], x]] (* Robert G. Wilson v, Sep 13 2007 *)
PROG
(PARI) a(n) = n!*sumdiv(n, d, (-1)^(d+1)/(d!*(n/d)!^d)); \\ Michel Marcus, Sep 29 2017
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Vladeta Jovovic, Sep 06 2007
EXTENSIONS
More terms from Robert G. Wilson v, Sep 13 2007
STATUS
approved