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 A033672 #19 Jul 11 2020 05:25:28 %S A033672 69,165,726,1353,4884,9768,18447,92928,175857,934428,1758867,9447438, %T A033672 17794887,96644658,182289327,906271608,1712444217,8836886388, %U A033672 17673772776,85401510447,159803020905,668823329856 %N A033672 Trajectory of 69 under map x->x + (x-with-digits-reversed). %H A033672 G. C. Greubel, <a href="/A033672/b033672.txt">Table of n, a(n) for n = 0..1000</a> %H A033672 <a href="/index/Res#RAA">Index entries for sequences related to Reverse and Add!</a> %t A033672 NestList[# + IntegerReverse@ # &, 69, 21] (* _Michael De Vlieger_, Oct 31 2018 *) %K A033672 nonn,base %O A033672 0,1 %A A033672 _N. J. A. Sloane_ %E A033672 Name clarified by _Michael De Vlieger_, Nov 02 2018