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 A378071 #8 Dec 05 2024 19:19:16
%S A378071 3,5,21,45,385,819,3465,7293,122265,255255,1062347,2204475,18253053,
%T A378071 37702175,155451825,319929885,10518906825,21585857535,88482569175,
%U A378071 181144476975,1481850184815,3027700543725,12361581411855,25214881603275,411156946959525,837470267650107
%N A378071 a(n) = denominator((4^(2*n+1)*n!^2)/((2*n+3)*(2*n)!)).
%p A378071 a := n -> (4^(2*n+1)*n!^2)/((2*n+3)*(2*n)!); seq(denom(a(n)), n = 0..25);
%t A378071 Table[Denominator[(4^(2*n + 1)*n!^2)/((2*n + 3)*(2*n)!)], {n, 0, 25}] (* _Michael De Vlieger_, Dec 05 2024 *)
%o A378071 (PARI) a(n) = denominator((4^(2*n+1)*n!^2)/((2*n+3)*(2*n)!)); \\ _Michel Marcus_, Dec 05 2024
%Y A378071 Cf. A102557 (numerator).
%K A378071 nonn,frac
%O A378071 0,1
%A A378071 _Peter Luschny_, Dec 05 2024