OFFSET
0,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..5000
EXAMPLE
.90422613822843452114627...
MATHEMATICA
RealDigits[N[Sum[((-1)^(n+1))/DivisorSigma[1, n]^n, {n, 1, 105}], 105]][[1]]
PROG
(PARI) suminf(n=1, (-1)^(n+1)/sigma(n)^n) \\ Michel Marcus, Apr 20 2018
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Michel Lagneau, Aug 04 2012
STATUS
approved