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 A120214 #10 Aug 16 2016 18:24:18 %S A120214 1013,3103,3015,5105,5017,7107,7019,9109,9021,1211,1123,3213,3125, %T A120214 5215,5127,7217,7129,9219,9131,1321,1233,3323,3235,5325,5237,7327, %U A120214 7239,9329,9241,1431,1343,3433,3345,5435,5347,7437,7349,9439,9351,1541,1453,3543 %N A120214 Start with 1013 and repeatedly reverse the digits and add 2 to get the next term. %C A120214 Let T(S,Q) be the sequence obtained by starting with S and repeatedly reversing the digits and adding Q to get the next term. This is T(1013,2). 1013 is the first S for which T(S,2) reaches a cycle of length 90. The cycle is simply the first 90 terms, which then repeat. A full period is given in the table. %H A120214 Klaus Brockhaus, <a href="/A120214/b120214.txt">Table of n, a(n) for n = 1,...,90</a> %H A120214 N. J. A. Sloane and others, <a href="/wiki/Sequences_of_RADD_type">Sequences of RADD type</a>, OEIS wiki. %H A120214 <a href="/index/Rec#order_90">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1). %t A120214 NestList[IntegerReverse[#]+2&,1013,50] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Aug 16 2016 *) %Y A120214 Cf. A117521, A118514, A120215, A120216, A120217, A120218. %K A120214 nonn,base %O A120214 1,1 %A A120214 _Klaus Brockhaus_, Jun 11 2006