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 A029584 #12 Jul 08 2025 19:14:53
%S A029584 2,1,0,2,6,16,60,272,1386,7936,50520,353792,2702766,22368256,
%T A029584 199360980,1903757312,19391512146,209865342976,2404879675440,
%U A029584 29088885112832,370371188237526,4951498053124096,69348874393137900
%N A029584 Expansion of cos x + tan x + sec x.
%C A029584 a(2n) = 2*A012007(n), a(2n+1) = A000182(n+1).
%H A029584 Harvey P. Dale, <a href="/A029584/b029584.txt">Table of n, a(n) for n = 0..485</a>
%t A029584 With[{nn=30},CoefficientList[Series[Cos[x]+Tan[x]+Sec[x],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jun 09 2025 *)
%K A029584 nonn
%O A029584 0,1
%A A029584 _N. J. A. Sloane_