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 A051621 #14 Sep 08 2022 08:44:59
%S A051621 1,13,221,4641,116025,3364725,111035925,4108329225,168441498225,
%T A051621 7579867420125,371413503586125,19684915690064625,1122040194333683625,
%U A051621 68444451854354701125,4448889370533055573125,306973366566780834545625
%N A051621 a(n) = (4*n+9)(!^4)/9(!^4), related to A007696(n+1) ((4*n+1)(!^4) quartic, or 4-factorials).
%C A051621 Row m=9 of the array A(5; m,n) := ((4*n+m)(!^4))/m(!^4), m >= 0, n >= 0.
%H A051621 G. C. Greubel, <a href="/A051621/b051621.txt">Table of n, a(n) for n = 0..363</a>
%F A051621 a(n) = ((4*n+9)(!^4))/9(!^4) = A007696(n+3)/(5*9).
%F A051621 E.g.f.: 1/(1-4*x)^(13/4).
%t A051621 s=1;lst={s};Do[s+=n*s;AppendTo[lst, s], {n, 12, 5!, 4}];lst (* _Vladimir Joseph Stephan Orlovsky_, Nov 08 2008 *)
%t A051621 With[{nn = 30}, CoefficientList[Series[1/(1 - 4*x)^(13/4), {x, 0, nn}], x]*Range[0, nn]!] (* _G. C. Greubel_, Aug 15 2018 *)
%o A051621 (PARI) x='x+O('x^30); Vec(serlaplace(1/(1-4*x)^(13/4))) \\ _G. C. Greubel_, Aug 15 2018
%o A051621 (Magma) m:=30; R<x>:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!(1/(1-4*x)^(13/4))); [Factorial(n-1)*b[n]: n in [1..m]]; // _G. C. Greubel_, Aug 15 2018
%Y A051621 Cf. A047053, A007696(n+1), A000407, A034176(n+1), A034177(n+1), A051617-A051622 (rows m=0..10).
%K A051621 easy,nonn
%O A051621 0,2
%A A051621 _Wolfdieter Lang_