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 A366114 #10 Sep 30 2023 13:08:50
%S A366114 1,2,4,7,9,2,-34,-130,-284,-284,730,4864,14860,27134,6462,-170865,
%T A366114 -771303,-2005828,-2751028,3491747,36288137,130265102,283131062,
%U A366114 210905402,-1317613954,-7461822262,-22297519418,-38398674146,10151248222,355843715494,1495838414326
%N A366114 Expansion of (1/x) * Series_Reversion( x*(1+x+x^2)/(1+x)^3 ).
%F A366114 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/2)} (-1)^k * binomial(n+k,k) * binomial(2*n-k+2,n-2*k).
%o A366114 (PARI) a(n) = sum(k=0, n\2, (-1)^k*binomial(n+k, k)*binomial(2*n-k+2, n-2*k))/(n+1);
%Y A366114 Cf. A127632, A364374, A366115.
%Y A366114 Cf. A279565.
%K A366114 sign
%O A366114 0,2
%A A366114 _Seiichi Manyama_, Sep 29 2023