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 A139281 #6 Jul 11 2015 16:32:32
%S A139281 0,1,2,3,4,5,6,7,8,9,0,11,2,3,14,5,6,17,8,9,0,2,22,6,8,25,2,14,28,8,
%T A139281 30,3,6,33,2,5,36,2,8,39,0,41,8,2,44,0,8,47,6,36,0,5,52,5,0,55,30,5,
%U A139281 58,0,60,6,2,63,8,30,66,8,6,69,0,71,14,2,74,5,8,77,30,63,0,8,82,8,6,85,6,30
%N A139281 If all digits are the same mod 3, stop; otherwise write down the number formed by the 1 mod 3 digits and the number formed by the 2 mod 3 digits and the number formed by the 3 mod 3 digits and multiply them; repeat.
%C A139281 Modulo 3 analog of A059707. The 1 mod 3 digits = {1,4,7}, 2 mod 3 digits = {2,5,8}, 3 mod 3 digits = {0, 3, 6, 9}. The fixed points begin: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 14, 17, 22, 25, 28, 30, 33, 36, 39, 41, 44, 47, 52, 55, 58.
%e A139281 a(57) = 5 because 5 and 7 are different mod 3, so 5*7 = 35; 3 and 5 are different mod 3, so 3*5 = 15; 1 and 5 are different mod 3, so 1*5 = 5, which is a fixed point.
%Y A139281 Cf. A010872, A059707, A059708, A059717.
%K A139281 base,easy,nonn
%O A139281 0,3
%A A139281 _Jonathan Vos Post_, Jun 06 2008
%E A139281 a(52) corrected and sequence extended by _Sean A. Irvine_, Sep 03 2009