%I #4 Mar 31 2012 13:22:18
%S 11,111,122,212,221,1111,1221,2122,2212,11111,12212,12221,13322,21221,
%T 22122,22331,111111,122122,122212,122221,212212,212221,221221,1111111,
%U 1221221,1222122,1222212,2122122,2122212,2122221,2212212,2212221
%N k th digit of a(n) = number of different digits within 2 places of k (not including k).
%e 2122 works, since 2=|{1,2}|, 1=|{2,2,2}|, 2=|{2,1,2}| and 2=|{1,2}|
%K base,easy,nonn
%O 0,1
%A _Erich Friedman_