OFFSET
0,2
EXAMPLE
r(n) = 1, 1/2, 1/6, 3/56, 1/60, 5/992, 1/672, 7/16256, 1/8160, 9/261632, ...
MAPLE
r := n -> `if`(n=0, 1, n/(4^n - 2^n)): seq(denom(r(n)), n=0..72);
PROG
(PARI) a(n) = if (n==0, 1, denominator(n / (4^n - 2^n))); \\ Michel Marcus, Aug 28 2020
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Peter Luschny, Aug 28 2020
STATUS
approved