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 A373906 #14 Jun 22 2024 14:12:18
%S A373906 1,1,1,1,2,8,29,85,212,476,1016,2172,4825,11213,26763,64095,151851,
%T A373906 354737,820328,1889968,4361521,10106859,23509678,54793282,127709888,
%U A373906 297336790,691382201,1606284377,3731020629,8668253125,20146856893,46840732201,108918637566,253262275888
%N A373906 a(n) = Sum_{k=0..floor(n/4)} binomial(n+2*k,n-4*k).
%H A373906 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6,-15,20,-14,6,-1).
%F A373906 a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 14*a(n-4) + 6*a(n-5) - a(n-6).
%F A373906 G.f.: 1/(1 - x - x^4/(1 - x)^5).
%o A373906 (PARI) a(n) = sum(k=0, n\4, binomial(n+2*k, n-4*k));
%Y A373906 Cf. A003269, A003522, A005252, A038503, A099131.
%Y A373906 Cf. A107025, A373904, A373905.
%K A373906 nonn,easy
%O A373906 0,5
%A A373906 _Seiichi Manyama_, Jun 22 2024