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 A371521 #15 Mar 27 2024 08:53:56
%S A371521 1,6,57,614,7158,88002,1123689,14760024,198172050,2707560544,
%T A371521 37522666803,526190125308,7452866846847,106465245105972,
%U A371521 1532129408941797,22191180837313808,323243244688652943,4732225866305323686,69591395772704207770,1027547992261749954798
%N A371521 G.f. A(x) satisfies A(x) = (1 + x*A(x) / (1-x))^6.
%F A371521 a(n) = 6 * Sum_{k=0..n} binomial(n-1,n-k) * binomial(6*k+5,k)/(5*k+6) = Sum_{k=0..n} binomial(n-1,n-k) * binomial(6*k+6,k)/(k+1).
%F A371521 G.f.: A(x) = B(x)^6 where B(x) is the g.f. of A349333.
%o A371521 (PARI) a(n) = 6*sum(k=0, n, binomial(n-1, n-k)*binomial(6*k+5, k)/(5*k+6));
%Y A371521 Cf. A349333, A371379, A371519, A371522, A371523.
%Y A371521 Cf. A045868, A371516, A371517, A371520.
%K A371521 nonn
%O A371521 0,2
%A A371521 _Seiichi Manyama_, Mar 26 2024