A258619 Decimal expansion of Sum_{k>=0} (1/A055209(k)).

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

Offset: 1

Author

Jani Melik, Jun 06 2015

Keywords

• nonn
• cons

Examples

			2.2569565016088514950284576370776548515676635143755759249....
		

Links

• G. C. Greubel, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A055209.

Programs

Magma

SetDefaultRealField(RealField(100)); b:=[1] cat [(&*[(Factorial(k))^2: k in [1..n]]): n in [1..60]];  (&+[1.0/b[k]: k in [1..50]]); // G. C. Greubel, Nov 28 2018

Mathematica

RealDigits[Sum[1/BarnesG[k + 2]^2, {k, 0, 80}], 10, 100][[1]] (* G. C. Greubel, Nov 28 2018 *)

PARI

default(realprecision, 100); sum(n=0,50, 1.0/prod(i=0, n, i!)^2) \\ G. C. Greubel, Nov 28 2018

Sage

def A055209(n) :
   return prod(factorial(i)^(2) for i in (0..n))
N(sum(1/A055209(n) for n in (0..12)), digits=105)

Extensions

Name corrected by Amiram Eldar, Nov 17 2020