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 A276989 #21 Nov 04 2024 11:13:37
%S A276989 1,1,2,5,14,43,140,474,1650,5863,21170,77441,286372,1068790,4020704,
%T A276989 15230470,58044354,222401745,856235030,3310615055,12849946406,
%U A276989 50051007940,195571906140,766413504375,3011469930300,11862075827007,46830440626612,185271557066226
%N A276989 Reversion of x - x^2 - x^6.
%H A276989 Robert Israel, <a href="/A276989/b276989.txt">Table of n, a(n) for n = 1..1615</a>
%H A276989 Vladimir Kruchinin, <a href="https://arxiv.org/abs/1211.3244">The method for obtaining expressions for coefficients of reverse generating functions</a>, arXiv:1211.3244 [math.CO], 2012.
%F A276989 a(n) = (Sum_{j=0..(n-1)/2} C(n-1-4*j,j)*C(2*n-4*j-2,n-1))/n.
%p A276989 S:= series(RootOf(x-x^2-x^6-t,x),t,41):
%p A276989 seq(coeff(S,t,i),i=1..40); # _Robert Israel_, Nov 04 2024
%t A276989 Table[Sum[Binomial[n-1-4*j,j]Binomial[2*n-4*j-2,n-1],{j,0,(n-1)/2}]/n, {n, 1, 25}]
%K A276989 nonn
%O A276989 1,3
%A A276989 _Benedict W. J. Irwin_, Sep 24 2016