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 A371543 #9 Mar 27 2024 08:53:39
%S A371543 1,4,18,100,611,3964,26796,186664,1330541,9657748,71138964,530417668,
%T A371543 3995461515,30359913132,232434013174,1791205897652,13883372595753,
%U A371543 108159238126644,846472588860134,6651825146945508,52465622957295300,415208597109815172
%N A371543 G.f. A(x) satisfies A(x) = (1 + x*A(x) / (1+x))^4.
%F A371543 a(n) = Sum_{k=0..n} (-1)^(n-k) * binomial(n-1,n-k) * binomial(4*k+4,k)/(k+1).
%o A371543 (PARI) a(n) = sum(k=0, n, (-1)^(n-k)*binomial(n-1, n-k)*binomial(4*k+4, k)/(k+1));
%Y A371543 Cf. A371517.
%K A371543 nonn
%O A371543 0,2
%A A371543 _Seiichi Manyama_, Mar 26 2024