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 A033661 #16 Jul 08 2025 19:55:28 %S A033661 31,44,88,176,847,1595,7546,14003,44044,88088,176176,847847,1596595, %T A033661 7553546,14007103,44177144,88354288,176599676,853595347,1597190705, %U A033661 6668108656,13236127322,35608290553,71117571206 %N A033661 Trajectory of 31 under map x->x + (x-with-digits-reversed). %H A033661 <a href="/index/Res#RAA">Index entries for sequences related to Reverse and Add!</a> %F A033661 a(n) = A033654(n-1) = A033652(n+1), n>1. [From _R. J. Mathar_, Oct 22 2008] %t A033661 NestList[#+IntegerReverse[#]&,31,30] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 23 2016 *) %K A033661 nonn,base %O A033661 0,1 %A A033661 _N. J. A. Sloane_