OFFSET
1,2
LINKS
FORMULA
c = Sum_{i >= 0} i!/(i+1)^(i+1).
Equals Integral_{-exp(-1)..0} (LambertW(x)-LambertW(-1,x))/(1+x)^2 dx. - Gleb Koloskov, Jun 12 2021
EXAMPLE
1.35909827711354826464352420607572078711282845105156869406...
MAPLE
evalf(Int(exp(-x)/(1-x*exp(-x)), x=0..infinity), 120); # Vaclav Kotesovec, May 19 2015
MATHEMATICA
c = NIntegrate[Exp[-x]/(1-x*Exp[-x]), {x, 0, Infinity}, WorkingPrecision -> 103]; RealDigits[c] // First
PROG
(PARI) default(realprecision, 120); sumpos(k=0, k!/(k+1)^(k+1)) \\ Vaclav Kotesovec, May 19 2015
CROSSREFS
KEYWORD
AUTHOR
Jean-François Alcover, May 19 2015
STATUS
approved