A234846 Decimal expansion of Sum_{n>=0} (2n)!/(n!)^3 = Sum_{n>=0} C(2n,n)/n!.

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

Offset

2,2

Links

Table of n, a(n) for n=2..88.

Formula

Equals e^2 * BesselI(0,2) = e^2 * Sum_{n>=0} 1/n!^2.

Equals e^4 * Sum_{n>=0} (-1)^n * C(2n,n)/n!. - Amiram Eldar, Nov 06 2020

Example

16.843983681258...
Equals 1/1 + 2/1 + 24/8 + 720/216 + 40320/13824 + 3628800/1728000 + ...

Mathematica

RealDigits[E^2*BesselI[0, 2], 10, 100][[1]] (* Amiram Eldar, Nov 06 2020 *)

Prog

(PARI) exp(2)*besseli(0, 2) \\ Charles R Greathouse IV, Feb 19 2014

Crossrefs

Cf. A000984, A070910.

Sequence in context: A352769 A335005 A321075 * A371467 A244054 A195701

Adjacent sequences: A234843 A234844 A234845 * A234847 A234848 A234849

Keyword

nonn,cons

Author

Richard R. Forberg, Dec 31 2013

Extensions

More terms from Jon E. Schoenfield, Mar 21 2021

Status

approved