A371937 Decimal expansion of Sum_{k>=0} (k+1)! / (2k)!.

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

Offset

1,1

Links

Table of n, a(n) for n=1..86.

Formula

Equals (1/8)(10 + 7 e^(1/4) sqrt(Pi) erf(1/2)).

Equals 1F1(2;1/2;1/4) . - R. J. Mathar, Jul 03 2024

Example

2.2865189388213215074057263454433597027480...

Maple

hypergeom([2], [1/2], 1/4) ; evalf(%) ; # R. J. Mathar, Jul 03 2024

Mathematica

s = Sum[(k + 1)!/(2 k)!, {k, 0, Infinity}]
d = N[s, 100]
First[RealDigits[d]]

Crossrefs

Cf. A371939.

Sequence in context: A024558 A238452 A103238 * A119999 A061828 A086535

Adjacent sequences: A371934 A371935 A371936 * A371938 A371939 A371940

Keyword

nonn,cons

Author

Clark Kimberling, Apr 27 2024

Status

approved