A336899 - OEIS

%I #9 Aug 28 2020 10:16:29

%S 1,2,6,56,60,992,672,16256,8160,261632,523776,4192256,1397760,

%T 67100672,134209536,1073709056,268431360,17179738112,3817734144,

%U 274877382656,54975528960,628292059136,8796090925056,70368735789056,11728123330560,1125899873288192,2251799780130816

%N a(n) = denominator(n / (4^n - 2^n)) for n > 0 and a(0) = 1.

%e r(n) = 1, 1/2, 1/6, 3/56, 1/60, 5/992, 1/672, 7/16256, 1/8160, 9/261632, ...

%p r := n -> `if`(n=0, 1, n/(4^n - 2^n)): seq(denom(r(n)), n=0..72);

%o (PARI) a(n) = if (n==0, 1, denominator(n / (4^n - 2^n))); \\ _Michel Marcus_, Aug 28 2020

%Y Cf. A336898 (numerator).

%K nonn,frac

%O 0,2

%A _Peter Luschny_, Aug 28 2020