A371941 - OEIS

%I #15 Jul 03 2024 08:04:54

%S 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 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 5,5,1,9,4,2,4,9,7,6,1,3,3,5,5,4,0,8

%N Decimal expansion of Sum_{k>=0} (k+1)! / (2*k+1)!.

%F Equals (1/4)*(2 + e^(1/4)*sqrt(Pi)*erf(1/2)).

%F Equals A248675/2. - _Hugo Pfoertner_, Apr 29 2024

%e 1.38844480470398986349062258180859403...

%p hypergeom([2], [3/2], 1/4) ; evalf(%) ; # _R. J. Mathar_, Jul 03 2024

%t s = Sum[(k + 1)!/(2 k+1)!, {k, 0, Infinity}]

%t d = N[s, 100]

%t First[RealDigits[d]]

%Y Cf. A248675, A371946.

%K nonn,cons

%O 1,2

%A _Clark Kimberling_, Apr 28 2024