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 A365256 #11 Jun 10 2024 00:03:57
%S A365256 2,6,7,4,4,3,7,7,8,1,3,8,3,5,4,4,2,7,8,7,9,8,0,3,7,5,6,1,1,5,9,2,5,3,
%T A365256 7,2,5,3,5,1,5,8,8,0,4,8,6,9,0,3,1,0,0,6,9,4,8,2,5,9,0,5,0,3,6,1,4,5,
%U A365256 1,8,6,1,4,1,8,9,7,6,6,1,1,8,7,8,9,7,5,3,6,2
%N A365256 Decimal expansion of Product_{n>=1} cos(Pi/(2*n+1)).
%F A365256 this * A365255 = A085365.
%e A365256 0.2674437781383544278798037561159253725...
%o A365256 (PARI) exp(sumpos(n=1, log(cos(Pi/(2*n+1))))) \\ _Michel Marcus_, Aug 29 2023
%Y A365256 Cf. A085365, A365255.
%K A365256 nonn,cons
%O A365256 0,1
%A A365256 _R. J. Mathar_, Aug 29 2023