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 A025644 #9 Aug 27 2025 08:01:09 %S A025644 0,1,2,0,3,1,4,2,0,5,3,1,6,4,2,0,7,5,3,1,8,6,4,2,0,9,7,5,3,1,10,8,6,4, %T A025644 2,0,11,9,7,5,3,1,12,10,8,6,4,2,0,13,11,9,7,5,3,1,14,12,10,8,6,4,2,0, %U A025644 15,13,11,9,7,5,3,1,16,14,12,10,8,6,4,2,0,17,15,13,11,9,7,5,3,1,18,16,14,12,10 %N A025644 Exponent of 3 (value of i) in n-th number of form 3^i*10^j. %C A025644 Starts like A082375 but the pattern then becomes more irregular ..5, 3, 1, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2, 23, 0, 21, 19, 17, 15, 13, 11, 9, 7, 5, 3, 24, 1, 22, 20,... - _R. J. Mathar_, Aug 27 2025 %Y A025644 Cf. A025616. %K A025644 nonn,changed %O A025644 1,3 %A A025644 _David W. Wilson_