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 A113328 #12 Sep 07 2024 21:09:55
%S A113328 1,3,18,117,801,5724,42633,331911,2717874,23620329,220260789,
%T A113328 2228505372,24681015981,300506801715,4017984855786,58675338993069,
%U A113328 928673101727001,15804592586240220,287174716511520033,5538727108037507535
%N A113328 a(n) = Sum_{k=0..n} 3^k*A111146(n,k).
%F A113328 G.f.: A(x) = 1/(1 - (3/2)*x*Sum_{k>=0} (k+2)!*x^k ).
%e A113328 A(x) = (1 + 3*x + 18*x^2 + 117*x^3 + 801*x^4 + 5724*x^5 +..)
%e A113328 = 1/(1 - 3/2!*x*(2! + 3!*x + 4!*x^2 + 5!*x^3 + 6!*x^4 +..) ).
%o A113328 (PARI) {a(n)=local(y=3,x=X+X*O(X^n)); polcoeff(1/(1 - y/(y-1)!*x*sum(k=0,n,(y-1+k)!*x^k)),n,X)}
%Y A113328 Cf. A111146, A113326, A113327 (y=2), A113329 (y=4), A113330 (y=5), A113331 (y=6).
%K A113328 nonn
%O A113328 0,2
%A A113328 _Philippe Deléham_ and _Paul D. Hanna_, Oct 26 2005