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 A365255 #8 Aug 29 2023 13:10:23
%S A365255 4,2,9,7,8,0,2,1,6,4,3,7,9,9,1,7,0,6,5,8,4,7,8,9,5,1,4,7,0,6,3,3,0,4,
%T A365255 8,8,4,9,2,5,3,7,6,3,9,7,4,5,4,8,6,5,7,1,0,8,2,7,6,5,7,3,7,4,3,6,8,8,
%U A365255 3,3,6,8,8,4,3,7,2,9,1,5,9,5,3,1,0
%N A365255 Decimal expansion of Product_{n>=2} cos(Pi/(2*n)).
%F A365255 this* A365256 = A085365.
%e A365255 0.4297802164379917065847895147063304...
%o A365255 (PARI) exp(sumpos(n=2, log(cos(Pi/(2*n))))) \\ _Michel Marcus_, Aug 29 2023
%Y A365255 Cf. A085365, A365256.
%K A365255 cons,nonn
%O A365255 0,1
%A A365255 _R. J. Mathar_, Aug 29 2023