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 A279238 #7 Dec 10 2016 22:40:06
%S A279238 1,1,-11,-343,871,54871,-12359,-102902159,-137687549,344971369,
%T A279238 20000206271,-34379966953693,-452834430450401,18163626705916771,
%U A279238 951418549566510481,-381881231033010506527,-4252976361755938012709,-218740547087902859463611
%N A279238 Numerators of coefficients in expansion of (cos x)/(1 + cos(sqrt(x))).
%H A279238 Clark Kimberling, <a href="/A279238/b279238.txt">Table of n, a(n) for n = 0..1000</a>
%e A279238 (1/2) + (1/8)x - (11/48)x^2 - (343/5760)x^3 + ... ; 1/2, 1/3, -11/48, 1/6480, -343/5760, ... = A279238/A279239.
%t A279238 z = 26; t = CoefficientList[Series[Cos[x]/(1 + Cos[Sqrt[x]]), {x, 0, z}], x];
%t A279238 Numerator[t] (* A279238 *)
%t A279238 Denominator[t] (* A279239 *)
%t A279238 %/2 (* A279240 *)
%Y A279238 Cf. A279239, A279240.
%K A279238 sign,easy,frac
%O A279238 0,3
%A A279238 _Clark Kimberling_, Dec 08 2016