OFFSET
1,1
LINKS
Steven R. Finch, Errata and Addenda to Mathematical Constants. 2.15 p. 20.
Gregorio Malajovich, On the expected number of zeros of nonlinear equations . arXiv:1106.6014v5 [math.AG] 28 Jun 2013 - arXiv.org
FORMULA
(1/Pi)*integral_{x^2+y^2<1} exp(2*x)/(1+exp(2*x))^2 dx dy = (1/(2*Pi))*integral_{x=-1..1} sqrt(1 - x^2)*sech(x)^2 dx.
EXAMPLE
2.029189212828897412828477207614873524683217519244552631788...
MATHEMATICA
(1/(2*Pi))*NIntegrate[Sqrt[1 - x^2]*Sech[x]^2, {x, -1, 1}, WorkingPrecision -> 102] // RealDigits // First
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Jean-François Alcover, Aug 13 2014
STATUS
approved