A025638 - OEIS

%I #10 Jun 08 2018 19:51:47

%S 0,1,2,3,0,4,1,5,2,6,3,0,7,4,1,8,5,2,9,6,3,0,10,7,4,1,11,8,5,2,12,9,6,

%T 3,0,13,10,7,4,1,14,11,8,5,2,15,12,9,6,3,0,16,13,10,7,4,1,17,14,11,8,

%U 5,2,18,15,12,9,6,3,19,0,16,13,10,7,4,20,1,17,14,11,8,5,21,2,18,15,12,9,6,22

%N Exponent of 2 (value of i) in n-th number of form 2^i*9^j.

%H Robert Israel, <a href="/A025638/b025638.txt">Table of n, a(n) for n = 1..10000</a>

%p N:= 10^8: # for 2^i*9^j <= N

%p B:= sort([seq(seq(2^i*9^j,i=0..ilog2(N/9^j)),j=0..floor(log[9](N)))]):

%p map(padic:-ordp,B,2); # _Robert Israel_, Jun 08 2018

%Y Cf. A025611.

%K nonn

%O 1,3

%A _David W. Wilson_