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 A368935 #11 Jan 10 2024 07:59:11
%S A368935 1,2,7,29,132,637,3200,16554,87576,471570,2575885,14238003,79487023,
%T A368935 447540164,2538352756,14489355578,83174465721,479842193453,
%U A368935 2780625587824,16178040713569,94467163314370,553430174678595,3251969073086610,19161172609833540,113186247571818096
%N A368935 Expansion of (1/x) * Series_Reversion( x * (1-x) * (1-x+x^3) ).
%F A368935 a(n) = (1/(n+1)) * Sum_{k=0..floor(n/3)} (-1)^k * binomial(n+k,k) * binomial(3*n-2*k+1,n-3*k).
%o A368935 (PARI) a(n) = sum(k=0, n\3, (-1)^k*binomial(n+k, k)*binomial(3*n-2*k+1, n-3*k))/(n+1);
%o A368935 (PARI) my(x='x+O('x^30)); Vec(serreverse(x*(1-x)*(1-x+x^3))/x) \\ _Michel Marcus_, Jan 10 2024
%Y A368935 Cf. A129442, A368936, A368937.
%Y A368935 Cf. A063033, A368931.
%K A368935 nonn
%O A368935 0,2
%A A368935 _Seiichi Manyama_, Jan 10 2024