OFFSET
2,1
FORMULA
Equals 2*cosh(Pi).
Equals 10 * Product_{k>=1} (1 + 4/(2*k+1)^2). - Amiram Eldar, Aug 09 2020
EXAMPLE
23.1839065510430412555035041051202753...
MAPLE
evalf(exp(Pi)+exp(-Pi)) ;
MATHEMATICA
RealDigits[Exp[Pi]+Exp[-Pi], 10, 120][[1]] (* Harvey P. Dale, Jan 28 2017 *)
PROG
(PARI) exp(Pi) + exp(-Pi) \\ Michel Marcus, Jun 27 2019
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
R. J. Mathar, Apr 01 2010
STATUS
approved