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 A366071 #13 Sep 29 2023 10:04:25
%S A366071 1,0,0,1,-1,1,3,-8,14,1,-49,144,-162,-139,1159,-2532,2036,6062,-26282,
%T A366071 47440,-11474,-190071,606163,-838984,-481092,5479390,-13618658,
%U A366071 13030368,28786262,-148598623,294393355,-128639411,-1086088045,3848604261,-5935686369,-1750697623
%N A366071 Expansion of (1/x) * Series_Reversion( x*(1+x-x^3)/(1+x) ).
%F A366071 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} (-1)^(n-k) * binomial(n+k,k) * binomial(n-2*k-1,n-3*k).
%o A366071 (PARI) a(n) = sum(k=0, n\3, (-1)^(n-k)*binomial(n+k, k)*binomial(n-2*k-1, n-3*k))/(n+1);
%Y A366071 Cf. A366095, A366096, A366097.
%Y A366071 Cf. A366101, A366102.
%Y A366071 Cf. A054514.
%K A366071 sign
%O A366071 0,7
%A A366071 _Seiichi Manyama_, Sep 29 2023