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 A071762 #7 May 15 2018 14:34:13
%S A071762 0,1,2,11,21,12,111,211,121,112,1111,2111,1211,1121,1112,11111,21111,
%T A071762 12111,11211,11121,11112,111111,211111,121111,112111,111211,111121,
%U A071762 111112,1111111,2111111,1211111,1121111,1112111,1111211,1111121,1111112
%N A071762 Leftmost 1 is converted to a 2, which then propagates one step at a time until it is rightmost; then it changes to a pair of 1's and the process repeats.
%C A071762 Arises in analysis of Bulgarian solitaire.
%H A071762 Harvey P. Dale, <a href="/A071762/b071762.txt">Table of n, a(n) for n = 0..1000</a>
%t A071762 f1[{a_,b_}]:={a,NestList[FromDigits[RotateRight[IntegerDigits[#]]]&, b, IntegerLength[ b]-1]}; Join[{0},f1/@Table[{FromDigits[PadRight[{},n,1]], FromDigits[ PadRight[{2},n,1]]},{n,7}]//Flatten] (* _Harvey P. Dale_, May 15 2018 *)
%Y A071762 Cf. A071761.
%K A071762 nonn,easy
%O A071762 0,3
%A A071762 _Allan C. Wechsler_, Jun 07 2002
%E A071762 More terms from _Sascha Kurz_, Jan 28 2003