OFFSET
1,2
REFERENCES
I.S. Gradshteyn and I.M. Ryzhik, Table of integrals, series and products, 5th edition, Academic Press, 1994, eq. (3.521.2).
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
E. D. Krupnikov and K. S. Kölbig, Some special cases of the generalized hypergeometric function (q+1)Fq, J. Comp. Appl. Math. 78 (1997) 79-95.
FORMULA
Equals Integral_{x=0..oo} x/cosh(x) dx.
Equals 2*A006752.
From Amiram Eldar, Aug 20 2020: (Start)
Equals Integral_{x=0..Pi/2} x/sin(x) dx.
Equals 1 + Integral_{x=0..oo} x * exp(-x) * tanh(x) dx. (End)
Equals 3F2(1/2,1,1;3/2,3/2;1) [Krupnikov]. - R. J. Mathar, May 13 2024
EXAMPLE
1.83193118835443803010920702986476822154...
MAPLE
evalf(2*Catalan) ;
MATHEMATICA
RealDigits[2 Catalan, 10, 100][[1]] (* Bruno Berselli, Feb 21 2013 *)
PROG
(PARI) default(realprecision, 100); 2*Catalan \\ G. C. Greubel, Aug 25 2018
(Magma) SetDefaultRealField(RealField(100)); R:=RealField(); 2*Catalan(R); // G. C. Greubel, Aug 25 2018
CROSSREFS
KEYWORD
AUTHOR
R. J. Mathar, Feb 21 2013
STATUS
approved