%I #7 Oct 19 2017 03:14:13
%S 1,3,2,3,1,2,1,2,3,1,1,2,1,1,2,1,2,3,1,1,1,2,1,1,1,2,1,1,2,1,2,3,1,1,
%T 1,1,2,1,1,1,1,2,1,1,1,2,1,1,2,1,2,3,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1,1,
%U 2,1,1,1,2,1,1,2,1,2,3,1,1,1,1,1,1,2,1,1,1,1,1,1,2,1,1,1,1,1,2,1,1,1
%N Start with the sequence a(1 to 4) = "1,3,2,3". Then in step s, append "1", "1,2", or "1,2,3", whichever ends with a(s+2).
%C a(n)=3 just if n=(k^3+3*k^2-4*k+12)/6.
%K nonn
%O 1,2
%A _Benoit Cloitre_, Apr 14 2003
%E Edited by _Don Reble_, Nov 02 2005