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 A353609 #11 May 08 2022 08:45:16
%S A353609 1,1,-14,393,-14744,972610,-74928944,9322093753,-1163849271296,
%T A353609 228519734620776,-44942000161435904,12717856972091286642,
%U A353609 -3539995034294896016384,1371560847857743301790928,-510461123036204706738612224,268938575250382935485761673113
%N A353609 Product_{n>=1} (1 + a(n)*x^(2*n)/(2*n)!) = cosh(x).
%t A353609 nn = 16; f[x_] := Product[(1 + a[n] x^(2 n)/(2 n)!), {n, 1, nn}]; sol = SolveAlways[0 == Series[f[x] - Cosh[x], {x, 0, 2 nn}], x]; Table[a[n], {n, 1, nn}] /. sol // Flatten
%Y A353609 Cf. A006973, A137852, A170912, A170913, A353607, A353608, A353610, A353611.
%K A353609 sign
%O A353609 1,3
%A A353609 _Ilya Gutkovskiy_, May 07 2022