This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A334366 #13 Jul 16 2020 02:25:25
%S A334366 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 A334366 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 A334366 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 A334366 Decimal expansion of Sum_{k>=0} 1/(4*k)!!.
%C A334366 This constant is transcendental.
%H A334366 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F A334366 Equals cosh(1/2).
%F A334366 Equals Product_{k>=0} 1 + 1/((2*k+1)*Pi)^2. - _Amiram Eldar_, Jul 16 2020
%e A334366 1/(2^0*0!) + 1/(2^2*2!) + 1/(2^4*4!) + ... = 1.1276259652063807852...
%t A334366 RealDigits[Cosh[1/2], 10, 110] [[1]]
%o A334366 (PARI) cosh(1/2) \\ _Michel Marcus_, Apr 25 2020
%Y A334366 Cf. A019774, A067624, A073743, A143280, A160327, A201505, A334367.
%K A334366 nonn,cons
%O A334366 1,3
%A A334366 _Ilya Gutkovskiy_, Apr 24 2020