A069267 a(n) = (2^(n-1)/(2n)!)*Product_{k=1..n} q(k) where q(n) is the denominator of B(2n), the 2n-th Bernoulli number.

3, 15, 42, 45, 66, 2730, 180, 765, 3990, 6930, 4140, 40950, 756, 1740, 57288, 58905, 630, 1919190, 16380, 284130, 595980, 434700, 118440, 4873050, 262548, 314820, 175560, 99180, 21240, 681440760, 2162160, 546975, 16504110, 217350, 421740

Offset

1,1

Comments

Lim_{n->inf} a(n)^(1/n) = 1.

Links

Table of n, a(n) for n=1..35.

Prog

(PARI) a(n) = (2^(n-1)/(2*n)!)*prod(k=1, n, denominator(bernfrac(2*k))); \\ Michel Marcus, Jan 04 2021

Crossrefs

Cf. A002445.

Sequence in context: A096742 A012256 A012222 * A348411 A059270 A219085

Adjacent sequences: A069264 A069265 A069266 * A069268 A069269 A069270

Keyword

easy,nonn

Author

Benoit Cloitre, Apr 14 2002

Extensions

Name edited by Michel Marcus, Jan 04 2021

Status

approved