A334366 - OEIS

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

%S 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,

%T 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,

%U 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

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

%C This constant is transcendental.

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

%F Equals cosh(1/2).

%F Equals Product_{k>=0} 1 + 1/((2*k+1)*Pi)^2. - _Amiram Eldar_, Jul 16 2020

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

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

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

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

%K nonn,cons

%O 1,3

%A _Ilya Gutkovskiy_, Apr 24 2020