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 A025640 #12 Jan 28 2021 21:36:49 %S A025640 0,1,0,2,1,0,3,2,1,0,4,3,2,1,5,0,4,3,2,6,1,5,0,4,3,7,2,6,1,5,0,4,8,3, %T A025640 7,2,6,1,5,0,9,4,8,3,7,2,6,1,10,5,0,9,4,8,3,7,2,11,6,1,10,5,0,9,4,8,3, %U A025640 12,7,2,11,6,1,10,5,0,9,4,13,8,3,12,7,2,11,6,1,10,5,0,14,9,4,13,8,3,12,7,2,11,6 %N A025640 Exponent of 3 (value of i) in n-th number of form 3^i*4^j. %H A025640 David A. Corneth, <a href="/A025640/b025640.txt">Table of n, a(n) for n = 1..10000</a> %e A025640 a(20) = 6 as the 20th number of the form 3^i * 4^j is 729 = 3^6 * 4^0 (See A025613). So the value of i in that factorization is the exponent of 3 which is 6. - _David A. Corneth_, Jan 28 2021 %Y A025640 Cf. A025613. %K A025640 nonn %O A025640 1,4 %A A025640 _David W. Wilson_