A248592 Denominators of the (simplified) rational numbers n*2^(n - 1)/(n - 1)! .

1, 1, 1, 3, 3, 5, 45, 315, 35, 567, 14175, 51975, 467775, 868725, 2837835, 638512875, 638512875, 1206079875, 97692469875, 371231385525, 441942125625, 17717861581875, 2143861251406875, 16436269594119375, 5917057053882975, 284473896821296875, 1780595872696265625

Offset: 1

Author

James Burling, Oct 09 2014

Keywords

• frac
• nonn

Links

• James Burling, Another Special Rational Sequence

Crossrefs

Cf. A248591 (numerators).

Has same start as A241591 but is a different sequence.

Programs

Maple

A248592 := proc(n)
    n*2^(n-1)/(n-1)! ;
    denom(%) ;
end proc:
seq(A248592(n),n=1..30) ; # R. J. Mathar, Oct 10 2014

PARI

vector(40, n, denominator(n*2^(n - 1)/(n - 1)!)) \\ Michel Marcus, Oct 09 2014

Formula

a(n) = denom(n * 2^(n - 1) / (n - 1)!).

a(n) = denom(g(1, n)) where g(m, n) = m if m = n; 2g(m + 1, n)/m otherwise.

Extensions

More terms from Michel Marcus, Oct 09 2014