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 A366096 #8 Sep 29 2023 10:04:34
%S A366096 1,2,5,15,51,187,719,2858,11650,48438,204630,875867,3790172,16554305,
%T A366096 72883035,323109570,1441152303,6462494515,29118219850,131761291852,
%U A366096 598529262016,2728346941040,12476533435028,57220220120080,263125059775970,1212942573227309
%N A366096 Expansion of (1/x) * Series_Reversion( x*(1+x-x^3)/(1+x)^3 ).
%F A366096 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} binomial(n+k,k) * binomial(2*n-k+2,n-3*k).
%o A366096 (PARI) a(n) = sum(k=0, n\3, binomial(n+k, k)*binomial(2*n-k+2, n-3*k))/(n+1);
%Y A366096 Cf. A366071, A366095, A366097.
%K A366096 nonn
%O A366096 0,2
%A A366096 _Seiichi Manyama_, Sep 29 2023