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 A072146 #13 Jul 11 2015 00:37:13 %S A072146 0,1,10,13,1011,1013,1028,100103,100107,100184,100368,100484,113008, %T A072146 150703,10000235,10000434,10001104,10001285,10001777,10001788, %U A072146 10002395,10002494,10109075,1000002787,1000011068,1000011159,1000012729,1001050344 %N A072146 Numbers n with property that n sets a new record for the length of the preperiodic part of the 'Reverse and Subtract' trajectory of n. %C A072146 A072147 gives the corresponding records. Since for small n the last term of the preperiodic part is a palindrome (cf. A072137), this sequence is a weak analog of A065198, which uses 'Reverse and Add'. %H A072146 Alexander Pesch, May 29 2007, <a href="/A072146/b072146.txt">Table of n, a(n) for n = 1..44</a> %e A072146 The preperiodic part of the trajectory of 13 has length 6: 13 -> 18 -> 63 -> 27 -> 45 -> 9; for k < 13 the preperiodic part has a smaller length (at most 2). %Y A072146 Cf. A072137, A072147, A065198. %K A072146 base,nonn %O A072146 1,3 %A A072146 _Klaus Brockhaus_, Jun 24 2002 %E A072146 a(19) = 10001777 inserted by _Alexander Pesch_, May 29 2007 %E A072146 Edited by _N. J. A. Sloane_, Dec 01 2007