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 A298244 #8 Aug 17 2019 03:48:17
%S A298244 1,1,4,30,320,4400,74016,1472240,33800192,879646464,25589632000,
%T A298244 822867814912,28982612385792,1109640105852928,45884917741981696,
%U A298244 2038015221365667840,96765606087737999360,4890992991269273403392,262201755871367895711744,14859866059895961631981568,887693530413229611155456000
%N A298244 a(n) = n! * [x^n] (sec(x) + tan(x))^n.
%H A298244 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%H A298244 <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a>
%F A298244 a(n) ~ n! * c * d^n / sqrt(n), where d = 3.063838405249746742835218125232... and c = 0.308377491585051819518915209... - _Vaclav Kotesovec_, Aug 17 2019
%t A298244 Table[n! SeriesCoefficient[(Sec[x] + Tan[x])^n, {x, 0, n}], {n, 0, 20}]
%Y A298244 Cf. A000111, A001250, A217066, A292758, A292976, A296793.
%Y A298244 Main diagonal of A322267.
%K A298244 nonn
%O A298244 0,3
%A A298244 _Ilya Gutkovskiy_, Jan 15 2018