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 A279240 #8 Jun 05 2024 18:11:40
%S A279240 1,4,24,2880,40320,7257600,479001600,697426329600,20922789888000,
%T A279240 261321375744000,221172909834240000,4496002911110430720000,
%U A279240 620448401733239439360000,806582922253211271168000000,304888344611713860501504000000,4244045756995056938180935680000000
%N A279240 Denominators of coefficients in expansion of (2 cos x)/(1 + cos(sqrt(x))).
%H A279240 Clark Kimberling, <a href="/A279240/b279240.txt">Table of n, a(n) for n = 0..1000</a>
%e A279240 (1/1) + (1/4)x - (11/24)x^2 - (343/2880)x^3 + (871/40320)x^4 + ... ; 1/1, 1/4, -11/24, -343/2880, ... = A279238/A279240.
%t A279240 CoefficientList[Series[2 Cos[x]/(1+Cos[Sqrt[x]]),{x,0,20}],x]//Denominator (* _Harvey P. Dale_, Jun 05 2024 *)
%Y A279240 Cf. A279238, A279239.
%K A279240 nonn,easy,frac
%O A279240 0,2
%A A279240 _Clark Kimberling_, Dec 08 2016
%E A279240 Prior Mathematica program corrected by _Harvey P. Dale_, Jun 05 2024