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 A367111 #10 Nov 05 2023 09:01:29
%S A367111 1,1,1,3,9,21,53,155,449,1273,3721,11155,33529,101245,309037,950587,
%T A367111 2936833,9117169,28448209,89134435,280252585,884123429,2797933733,
%U A367111 8879167067,28249550913,90091462761,287946752601,922194331891,2959055180953,9511538457229
%N A367111 G.f. satisfies A(x) = 1 + x*A(x) + 2*x^3*A(x)^3.
%F A367111 a(n) = Sum_{k=0..floor(n/3)} 2^k * binomial(n,3*k) * A001764(k).
%o A367111 (PARI) a(n) = sum(k=0, n\3, 2^k*binomial(n, 3*k)*binomial(3*k, k)/(2*k+1));
%Y A367111 Cf. A001764, A071879, A367112, A367113.
%Y A367111 Cf. A190590.
%K A367111 nonn,easy
%O A367111 0,4
%A A367111 _Seiichi Manyama_, Nov 05 2023