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 A025638 #10 Jun 08 2018 19:51:47 %S A025638 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 A025638 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 A025638 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 A025638 Exponent of 2 (value of i) in n-th number of form 2^i*9^j. %H A025638 Robert Israel, <a href="/A025638/b025638.txt">Table of n, a(n) for n = 1..10000</a> %p A025638 N:= 10^8: # for 2^i*9^j <= N %p A025638 B:= sort([seq(seq(2^i*9^j,i=0..ilog2(N/9^j)),j=0..floor(log[9](N)))]): %p A025638 map(padic:-ordp,B,2); # _Robert Israel_, Jun 08 2018 %Y A025638 Cf. A025611. %K A025638 nonn %O A025638 1,3 %A A025638 _David W. Wilson_