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 A001728 #10 Feb 01 2022 01:23:58
%S A001728 1,15,1185,230895,83860545,48942778575,41893214676705,
%T A001728 49441928730798255,76946148390480577665,152682246738275154625935,
%U A001728 376229085883258481118811425,1127131459348047116845576437615,4034538627668651235506091915425985
%N A001728 Expansion of cos x / cos 4x.
%H A001728 T. D. Noe, <a href="/A001728/b001728.txt">Table of n, a(n) for n = 0..50</a>
%t A001728 nn = 22; t = Range[0, nn]! CoefficientList[Series[Cos[x]/Cos[4 x], {x, 0, nn}], x]; Take[t, {1, nn, 2}];
%Y A001728 Bisection of A000813.
%K A001728 nonn
%O A001728 0,2
%A A001728 _N. J. A. Sloane_