%I #13 Jul 16 2020 02:25:29

%S 5,2,1,0,9,5,3,0,5,4,9,3,7,4,7,3,6,1,6,2,2,4,2,5,6,2,6,4,1,1,4,9,1,5,

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

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

%N Decimal expansion of Sum_{k>=0} 1/(4*k+2)!!.

%C This constant is transcendental.

%H <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>

%F Equals sinh(1/2).

%F Equals (1/2) * Product_{k>=1} 1 + 1/(2*k*Pi)^2. - _Amiram Eldar_, Jul 16 2020

%e 1/(2^1*1!) + 1/(2^3*3!) + 1/(2^5*5!) + ... = 0.52109530549374736162242...

%t RealDigits[Sinh[1/2], 10, 110] [[1]]

%o (PARI) sinh(1/2) \\ _Michel Marcus_, Apr 25 2020

%Y Cf. A019774, A067626, A073742, A143280, A160327, A201504, A334366.

%K nonn,cons

%O 0,1

%A _Ilya Gutkovskiy_, Apr 24 2020