A334366 Decimal expansion of Sum_{k>=0} 1/(4*k)!!.

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

Offset

1,3

Comments

This constant is transcendental.

Links

Table of n, a(n) for n=1..110.

Index entries for transcendental numbers

Formula

Equals cosh(1/2).

Equals Product_{k>=0} 1 + 1/((2*k+1)*Pi)^2. - Amiram Eldar, Jul 16 2020

Example

1/(2^0*0!) + 1/(2^2*2!) + 1/(2^4*4!) + ... = 1.1276259652063807852...

Mathematica

RealDigits[Cosh[1/2], 10, 110] [[1]]

Prog

(PARI) cosh(1/2) \\ Michel Marcus, Apr 25 2020

Crossrefs

Cf. A019774, A067624, A073743, A143280, A160327, A201505, A334367.

Sequence in context: A259235 A264692 A021366 * A350761 A135155 A308705

Adjacent sequences: A334363 A334364 A334365 * A334367 A334368 A334369

Keyword

nonn,cons

Author

Ilya Gutkovskiy, Apr 24 2020

Status

approved