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 #7 Aug 23 2024 05:29:16
%S 1,0,2,5,5,1,9,7,4,5,6,9,3,6,8,7,1,4,0,2,3,7,6,3,1,3,0,3,0,5,6,8,6,2,
%T 2,9,2,9,1,3,6,2,6,4,9,9,2,3,7,0,9,6,2,3,0,2,2,7,9,5,3,9,7,4,1,5,5,2,
%U 4,9,2,7,2,4,5,0,5,4,1,5,5,3,4,7,3,6,4,9,9,9,5,2,8
%N Decimal expansion of Sum_{n>=1} 3^n*(n!)^2/(2n)!.
%D Alexander Apelblat, Tables of Integrals and Series, Harri Deutsch, 1996, 4.1.34.
%F Equals 3 + 10 * A019694 * A020760.
%e 10.255197456936871...
%p evalf(4*Pi/3^(1/2) + 3, 100);
%t RealDigits[4*Pi/Sqrt[3] + 3, 10, 120][[1]] (* _Amiram Eldar_, Aug 23 2024 *)
%Y Cf. A019694, A020760.
%K cons,easy,nonn
%O 2,3
%A _R. J. Mathar_, Feb 08 2009