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%I #5 Jun 17 2013 14:34:35
%S 2,3,5,6,8,9,11,12,13,15,16,18,19,21,22,23,25,26,28,29,31,32,33,35,36,
%T 38,39,41,42,43,45,46,48,49,51,52,53,55,56,58,59,61,62,63,65,66,68,69,
%U 71,72,73,75,76,78,79,81,82,83,85,86,88,89,91,92,93,95
%N Position of 2^n in the joint ranking of all the numbers 2^j for j>=0 and 5^k for k>=1; complement of A123384.
%C a(n) = 1 + A066344(n).
%H Clark Kimberling, <a href="/A226721/b226721.txt">Table of n, a(n) for n = 1..2000</a>
%F a(n) = floor(n*(1 + log_c(b)).
%e The joint ranking of the powers of 2 and of 5 begins like this: 1, 2, 4, 5, 8, 16, 25, 32, 64, 125, 128, 256, 512. The numbers 2^n for n >= 1 are in positions 2, 3, 5, 6, 8, 9, 11, 12, 13.
%t b = 2; c=5; Floor[1 + Range[0, 100]*(1 + Log[b, c])] (* A123384 *)
%t Floor[1 + Range[1, 100]*(1 + Log[c, b])] (* A226721 *)
%Y Cf. A123384, A226720.
%K nonn,easy
%O 1,1
%A _Clark Kimberling_, Jun 16 2013
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