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 A367660 #8 Nov 26 2023 08:37:28
%S A367660 1,2,4,8,16,34,72,152,320,676,1428,3016,6368,13448,28400,59976,126656,
%T A367660 267472,564848,1192848,2519056,5319746,11234248,23724504,50101440,
%U A367660 105804296,223437672,471856016,996466240,2104338904,4443946064,9384731992,19818691136
%N A367660 G.f. A(x) satisfies A(x) = 1 / (1 - x - x * A(x^4)).
%F A367660 a(0) = 1; a(n) = a(n-1) + Sum_{k=0..floor((n-1)/4)} a(k) * a(n-1-4*k).
%F A367660 a(0) = 1, a(1) = 2, a(2) = 4, a(3) = 8; a(n) = a(n-4) + Sum_{k=0..n-1} a(floor(k/4)) * a(n-1-k).
%o A367660 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, (i-1)\4, v[j+1]*v[i-4*j])); v;
%Y A367660 Cf. A349365, A367659, A367661.
%K A367660 nonn
%O A367660 0,2
%A A367660 _Seiichi Manyama_, Nov 26 2023