OFFSET
2,1
COMMENTS
This constant and the constant of A128892 are connected by the equation Sum_{n>=0} S_n - 2*Pi*Sum{n>=0} V_n = 2, where S_n and V_n are respectively the area and volume of an n-dimensional sphere of unit radius. - Philippe A.J.G. Chevalier, Dec 17 2015
LINKS
G. C. Greubel, Table of n, a(n) for n = 2..5002
FORMULA
Sum_{n>=0} Pi^(n/2)/Gamma(n/2+1), where the summand is the volume of a ball in n dimensions. - Jean-François Alcover, Apr 14 2015
EXAMPLE
45.9993260893828553662740531827001975528647961835874132957770302131...
MATHEMATICA
RealDigits[E^Pi*(1 + Erf[Sqrt[Pi]]), 10, 111][[1]] (* Robert G. Wilson v, Apr 22 2007 *)
PROG
(MATLAB) exp(pi)*(1+erf(sqrt(pi))) \\ Altug Alkan, Nov 11 2015
(PARI) exp(Pi)*(2-erfc(sqrt(Pi))) \\ Michel Marcus, Nov 11 2015
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Philippe Deléham, Apr 20 2007
EXTENSIONS
More terms from Robert G. Wilson v, Apr 22 2007
STATUS
approved