This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A025643 #13 Jun 11 2015 03:13:30 %S A025643 0,1,0,2,1,3,0,2,4,1,3,5,0,2,4,6,1,3,5,7,0,2,4,6,8,1,3,5,7,9,0,2,4,6, %T A025643 8,10,1,3,5,7,9,11,0,2,4,6,8,10,12,1,3,5,7,9,11,13,0,2,4,6,8,10,12,14, %U A025643 1,3,5,7,9,11,13,15,0,2,4,6,8,10,12,14,16,1,3,5,7,9,11,13,15,17,0,2,4,6,8,10 %N A025643 Exponent of 3 (value of i) in n-th number of form 3^i*8^j. %H A025643 Robert Israel, <a href="/A025643/b025643.txt">Table of n, a(n) for n = 1..10000</a> %p A025643 N:= 10^40: # include entries for all 3^i*8^j <= N %p A025643 map(t -> t[1],sort([seq(seq([i,j],j=0..floor(log[8](N/3^i))),i=0..floor(log[3](N)))],(s,t) -> 3^s[1]*8^s[2]<=3^t[1]*8^t[2])); %Y A025643 Cf. A025615, A025672. %K A025643 nonn %O A025643 1,4 %A A025643 _David W. Wilson_