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 A344057 #16 May 12 2021 20:38:35
%S A344057 1,2,24,360,8064,259200,11404800,660441600,48771072000,4477184409600,
%T A344057 500391198720000,66920738734080000,10554356508917760000,
%U A344057 1938789402181632000000,410402940653807861760000,99180710658003566592000000,27141314475238493257728000000
%N A344057 a(n) = (2*n)! / CatalanNumber(n - 1) for n >= 1 and a(0) = 1.
%F A344057 a(n) = A010050(n)/A000108(n-1) for n>=1. - _Michel Marcus_, May 12 2021
%F A344057 a(n) = 2*n*(2*n-1)*(n-1)!*n! = 2*n^2*(2*n-1)*((n-1)!)^2 for n > 0. a(n) = a(n-1)*n^2*(2*n - 1)/(2*n - 3) for n > 1. - _Chai Wah Wu_, May 12 2021
%t A344057 a[n_] := (2 n)! / CatalanNumber[n - 1]; a[0] := 1; Table[a[n], {n, 0, 16}]
%o A344057 (Python)
%o A344057 from math import factorial
%o A344057 def A344057(n):
%o A344057 return 1 if n == 0 else 2*n**2*(2*n-1)*factorial(n-1)**2 # _Chai Wah Wu_, May 12 2021
%Y A344057 Cf. A000108, A010050.
%K A344057 nonn
%O A344057 0,2
%A A344057 _Peter Luschny_, May 12 2021