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 A025639 #7 Jul 06 2025 10:15:02 %S A025639 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 A025639 3,13,0,10,7,4,14,1,11,8,5,15,2,12,9,6,16,3,13,0,10,7,17,4,14,1,11,8, %U A025639 18,5,15,2,12,9,19,6,16,3,13,0,10,20,7,17,4,14,1,11,21,8,18,5,15,2,12,22,9,19 %N A025639 Exponent of 2 (value of i) in n-th number of form 2^i*10^j. %Y A025639 Cf. A025612. %K A025639 nonn %O A025639 1,3 %A A025639 _David W. Wilson_