Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #12 Mar 25 2013 10:36:40
%S 5,5,7,3,1,6,9,6,6,4,3,1,0,0,3,9,7,5,3,2,5,7,9,0,4,0,4,9,7,7,5,5,8,2,
%T 4,0,0,5,3,8,3,8,5,3,1,3,5,6,4,6,6,5,3,4,3,0,3,2,4,8,1,2,0,6,4,1,8,2,
%U 9,0,3,0,7,3,2,8,3,4,5,3,5,8,4,2,2,4,5
%N Decimal expansion of sum(1/Gamma(n/2), n>=1).
%H Vincenzo Librandi, <a href="/A222392/b222392.txt">Table of n, a(n) for n = 1..5000</a>
%F Equals (1+erf(1))*e+1/sqrt(Pi), where erf is the error function (see A099286).
%e 5.57316966431003975325790404977558240053838531356466534303248120641829030...
%t RealDigits[(1 + Erf[1]) E + 1/Sqrt[Pi], 10, 90][[1]]
%Y Cf. A222391.
%Y Cf. A001113, sum(1/Gamma(n), n>=1).
%K nonn,cons
%O 1,1
%A _Bruno Berselli_, Mar 19 2013