A308715 Decimal expansion of cosh(Pi/2).

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

Offset

1,1

Links

Table of n, a(n) for n=1..120.

Formula

Equals Product_{k>=1} (1 + 1/(2*k - 1)^2).

Equals Product_{k>=0} (1 + 1/A016754(k)).

Example

2.50917847865805678200999564326940594821202435...

Mathematica

RealDigits[Cosh[Pi/2], 10, 120][[1]]

Prog

(PARI) cosh(Pi/2) \\ Michel Marcus, Jun 20 2019

Crossrefs

Cf. A003881, A016754, A156648, A308716.

Sequence in context: A020836 A349353 A111466 * A201745 A192042 A214119

Adjacent sequences: A308712 A308713 A308714 * A308716 A308717 A308718

Keyword

nonn,cons

Author

Ilya Gutkovskiy, Jun 19 2019

Status

approved