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 A384303 #13 May 26 2025 07:55:24
%S A384303 1,20,5040,3603600,5079110400,11861676288000,41430393164160000,
%T A384303 202250096145377280000,1315041316842168115200000,
%U A384303 10985733772470225465016320000,114660755112113373922453094400000,1462160421974232524852811030528000000,22368646191981329482560015901851648000000
%N A384303 a(n) = Product_{k=0..2*n-1} (3*n+k+1).
%F A384303 a(n) = RisingFactorial(3*n+1,2*n).
%F A384303 a(n) = (2*n)! * [x^(2*n)] 1/(1 - x)^(3*n+1).
%F A384303 a(n) = (5*n)!/(3*n)!.
%F A384303 D-finite with recurrence 3*(3*n-1)*(3*n-2)*a(n) -5*(5*n-4)*(5*n-3)*(5*n-2)*(5*n-1)*a(n-1)=0. - _R. J. Mathar_, May 26 2025
%o A384303 (PARI) a(n) = (5*n)!/(3*n)!;
%Y A384303 Cf. A384300, A384301, A384302.
%Y A384303 Cf. A166384.
%K A384303 nonn,easy
%O A384303 0,2
%A A384303 _Seiichi Manyama_, May 25 2025