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 A026033 #11 Apr 30 2014 01:31:34 %S A026033 1,4,28,220,1819,15484,134320,1180764,10482340,93766288,843822148, %T A026033 7631018564,69291185474,631334484200,5769124912320,52851389067420, %U A026033 485242722376524,4463782855666480,41133265444555120 %N A026033 C(4n,n) - C(4n,n-4). %F A026033 G.f.: (g-2)*(2-2*g+g^2)*g^2/(3*g-4) where g = 1+x*g^4 is the g.f. of A002293. - Mark van Hoeij, Nov 11 2011 %Y A026033 a(n) = T(4n, n), where T is defined in A026022. %K A026033 nonn %O A026033 0,2 %A A026033 _Clark Kimberling_ %E A026033 More terms from _Ralf Stephan_, Jan 09 2005