OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
Eric Weisstein's MathWorld, Beta Function
FORMULA
Also equals sqrt(Pi)*Sum_{n>=0} (Sum_{k>=n} (-1)^n*k!/((2*k)!*Beta(n + 1, 1/2 - n)*(k - n)!)), where Beta is the Euler beta function.
EXAMPLE
1.661095845547755702622913937539905964012699504156022...
MAPLE
evalf(Int(exp(-x^2)*cosh(sqrt(1+x^2)), x=0..infinity), 120); # Vaclav Kotesovec, Jun 02 2015
MATHEMATICA
NIntegrate[Exp[-x^2]*Cosh[Sqrt[1 + x^2]], {x, 0, Infinity}, WorkingPrecision -> 105] // RealDigits // First
CROSSREFS
KEYWORD
AUTHOR
Jean-François Alcover, Jun 02 2015
STATUS
approved