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 A381985 #17 Mar 14 2025 08:59:09
%S A381985 1,2,13,217,5937,223641,10725433,625007993,42883208609,3386452550689,
%T A381985 302545287708201,30170153462509545,3322052185576104049,
%U A381985 400328811249634307249,52406094009429908677049,7405663486143907784247481,1123601498350780798756198209,182173718779147621454796872769
%N A381985 E.g.f. A(x) satisfies A(x) = exp(x) * B(x*A(x)), where B(x) = 1 + x*B(x)^3 is the g.f. of A001764.
%F A381985 Let F(x) be the e.g.f. of A364987. F(x) = B(x*A(x)) = exp( 1/3 * Sum_{k>=1} binomial(3*k,k) * (x*A(x))^k/k ).
%F A381985 a(n) = n! * Sum_{k=0..n} (k+1)^(n-k) * A002293(k)/(n-k)!.
%o A381985 (PARI) a(n) = n!*sum(k=0, n, (k+1)^(n-k)*binomial(4*k+1, k)/((4*k+1)*(n-k)!));
%Y A381985 Cf. A381984, A381986.
%Y A381985 Cf. A001764, A002293, A346646, A364987.
%K A381985 nonn
%O A381985 0,2
%A A381985 _Seiichi Manyama_, Mar 11 2025