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 A128275 #6 Apr 08 2021 12:15:19
%S A128275 1,5,121,1369,698161,22394737,25947503401,29819441791,
%T A128275 3389281372287841,354891998735343073,1147649139272698443481,
%U A128275 179707467079684030326841,76137452589606191547280211,183280927961986287722231696209,1163176750283121903011836076436361
%N A128275 Absolute values of numerators of series expansion of sinh(x)/sqrt((cosh(x))^2+(sinh(x))^2) about 0 (odd indexed coefficients only).
%t A128275 Series[Sinh[x]/(Sqrt[Cosh[x]^2 + Sinh[x]^2]), {x, 0, 20}]
%Y A128275 Cf. A012085, A012193, A128274.
%K A128275 nonn
%O A128275 0,2
%A A128275 _Artur Jasinski_, Feb 22 2007
%E A128275 Offset 0 and more terms from _Alois P. Heinz_, Apr 08 2021