A378071 a(n) = denominator((4^(2*n+1)*n!^2)/((2*n+3)*(2*n)!)).

3, 5, 21, 45, 385, 819, 3465, 7293, 122265, 255255, 1062347, 2204475, 18253053, 37702175, 155451825, 319929885, 10518906825, 21585857535, 88482569175, 181144476975, 1481850184815, 3027700543725, 12361581411855, 25214881603275, 411156946959525, 837470267650107

Offset: 0

Author

Peter Luschny, Dec 05 2024

Keywords

• nonn
• frac

Crossrefs

Cf. A102557 (numerator).

Programs

Maple

a := n -> (4^(2*n+1)*n!^2)/((2*n+3)*(2*n)!); seq(denom(a(n)), n = 0..25);

Mathematica

Table[Denominator[(4^(2*n + 1)*n!^2)/((2*n + 3)*(2*n)!)], {n, 0, 25}] (* Michael De Vlieger, Dec 05 2024 *)

PARI

a(n) = denominator((4^(2*n+1)*n!^2)/((2*n+3)*(2*n)!)); \\ Michel Marcus, Dec 05 2024