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 A381941 #12 Mar 11 2025 07:59:16
%S A381941 1,3,10,71,644,6461,68971,768054,8820281,103694479,1241799996,
%T A381941 15095075897,185769856443,2310006893997,28978952155943,
%U A381941 366315306556482,4661272734504606,59659914501348239,767539555514812321,9920124234695256009,128744011085858468131,1677087982747514335025
%N A381941 G.f. A(x) satisfies A(x) = (1 + x)^2 * B(x*A(x)), where B(x) is the g.f. of A002293.
%F A381941 a(n) = Sum_{k=0..n} binomial(5*k+1,k) * binomial(2*k+2,n-k)/(5*k+1).
%o A381941 (PARI) a(n) = sum(k=0, n, binomial(5*k+1, k)*binomial(2*k+2, n-k)/(5*k+1));
%Y A381941 Cf. A366694, A367640, A381938.
%Y A381941 Cf. A002293.
%K A381941 nonn
%O A381941 0,2
%A A381941 _Seiichi Manyama_, Mar 10 2025