OFFSET
0,1
COMMENTS
Let Xi(s) = -(s + 1/2)*zeta(1/2 - s)*(1/4 - s/2)! / Pi^(1/4 - s/2) be Riemann's (uppercase) Xi function, then the given constant equals Xi(0). - Peter Luschny, Jun 28 2021
LINKS
Eric Weisstein's World of Mathematics, Xi-Function
FORMULA
Equals -(1/4)!*zeta(1/2)/(2*Pi^(1/4)). - Peter Luschny, Jun 27 2021
EXAMPLE
0.49712077818831410991277373968539771980729360955770518593323423...
MATHEMATICA
RealDigits[RiemannXi[1/2], 10, 102][[1]] (* Jean-François Alcover, Nov 04 2017 *)
PROG
(PARI) -(gamma(1/4)*zeta(1/2))/(8*Pi^(1/4)) \\ Michel Marcus, Nov 04 2017
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Eric W. Weisstein, Dec 27 2005
STATUS
approved