login
a(n) = denominator(c(n)) where c(n) = 1 if n=1, otherwise if n < 3*2^floor(log_2(n)-1) then c(n) = (c(floor(n/2))+c(floor((n+1)/2)))/2 otherwise c(n) = c(n-2^floor(log_2(n)))+1.
3

%I #14 Jun 30 2021 05:30:18

%S 1,1,1,1,2,1,1,1,4,2,4,1,2,1,1,1,8,4,8,2,8,4,8,1,4,2,4,1,2,1,1,1,16,8,

%T 16,4,16,8,16,2,16,8,16,4,16,8,16,1,8,4,8,2,8,4,8,1,4,2,4,1,2,1,1,1,

%U 32,16,32,8,32,16,32,4,32,16,32,8,32,16,32,2,32,16,32,8,32,16,32,4,32,16

%N a(n) = denominator(c(n)) where c(n) = 1 if n=1, otherwise if n < 3*2^floor(log_2(n)-1) then c(n) = (c(floor(n/2))+c(floor((n+1)/2)))/2 otherwise c(n) = c(n-2^floor(log_2(n)))+1.

%C See A140129 for further comments and examples.

%H Reinhard Zumkeller, <a href="/A140130/b140130.txt">Table of n, a(n) for n = 1..8191</a>

%F a(n) = if n=1 then 1 else if n < 3*2^floor(log_2(n)-1) then (if n mod 2 = 0 then a(n/2) else 2^floor(log_2(n)-1)) else a(n-floor(log_2(n))).

%F For n>1: a(A023758(n)) = 1.

%Y Cf. A140129 (numerators).

%K nonn,frac

%O 1,5

%A _Reinhard Zumkeller_, May 14 2008