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 A128274 #11 Jun 07 2025 23:55:38
%S A128274 1,1,17,721,58337,7734241,218014151,419784870961,153563504618177,
%T A128274 10300599833780983,2486497854930863041,30262124466958766778001,
%U A128274 3711710439292601861342231,26350476755161831091778460321,31166629149666821954776191205937,45673109693364177065089340171611
%N A128274 Absolute values of numerators of series expansion of cosh(x)/sqrt((cosh(x))^2+(sinh(x))^2) about 0 (even-indexed coefficients only).
%t A128274 Series[Cosh[x]/(Sqrt[Cosh[x]^2 + Sinh[x]^2]), {x, 0, 20}]
%Y A128274 Cf. A012085, A012193, A128275.
%K A128274 nonn
%O A128274 0,3
%A A128274 _Artur Jasinski_, Feb 22 2007
%E A128274 Offset 0 and more terms from _Alois P. Heinz_, Apr 08 2021