This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A371941 #15 Jul 03 2024 08:04:54
%S A371941 1,3,8,8,4,4,4,8,0,4,7,0,3,9,8,9,8,6,3,4,9,0,6,2,2,5,8,1,8,0,8,5,9,4,
%T A371941 0,3,0,9,2,6,9,2,4,9,1,8,3,2,5,4,8,0,6,5,5,6,6,3,5,2,8,7,5,4,7,9,8,0,
%U A371941 5,5,1,9,4,2,4,9,7,6,1,3,3,5,5,4,0,8
%N A371941 Decimal expansion of Sum_{k>=0} (k+1)! / (2*k+1)!.
%F A371941 Equals (1/4)*(2 + e^(1/4)*sqrt(Pi)*erf(1/2)).
%F A371941 Equals A248675/2. - _Hugo Pfoertner_, Apr 29 2024
%e A371941 1.38844480470398986349062258180859403...
%p A371941 hypergeom([2], [3/2], 1/4) ; evalf(%) ; # _R. J. Mathar_, Jul 03 2024
%t A371941 s = Sum[(k + 1)!/(2 k+1)!, {k, 0, Infinity}]
%t A371941 d = N[s, 100]
%t A371941 First[RealDigits[d]]
%Y A371941 Cf. A248675, A371946.
%K A371941 nonn,cons
%O A371941 1,2
%A A371941 _Clark Kimberling_, Apr 28 2024