%I #9 Jun 17 2015 11:17:20
%S 1,1,2,3,4,3,2,1,1,1,1,2,3,4,3,2,1,1,2,2,2,4,4,4,2,2,2,3,3,3,4,4,4,3,
%T 3,3,4,4,4,4,4,4,4,4,4,3,3,3,4,4,4,3,3,3,2,2,2,4,4,4,2,2,2,1,1,2,3,4,
%U 3,2,1,1,1,1,2,3,4,3,2,1,1
%N 4-symbol substitution made from Cantor matrix by one level matrix self-similarity.
%C Matrix: M={{4, 2,2 1}, {0, 6, 0, 3}, {0, 0, 6, 3}, {0, 0, 0, 9}} Characteristic Polynomial: -x^4+25*x^3-228*x^2+900x-1296
%H F. M. Dekking, <a href="http://dx.doi.org/10.1016/0001-8708(82)90066-4">Recurrent Sets</a>, Advances in Mathematics, vol. 44, no.1, April 1982, page 85, section 4.15, see Cantor set.
%F 1->{1, 1, 2, 3, 4, 3, 2, 1, 1}, 2->{2, 2, 2, 4, 4, 4, 2, 2, 2}, 3->{3, 3, 3, 4, 4, 4, 3, 3, 3}, 4->{4, 4, 4, 4, 4, 4, 4, 4, 4}
%t s[1] = {1, 1, 2, 3, 4, 3, 2, 1, 1}; s[2] = {2, 2, 2, 4, 4, 4, 2, 2, 2}; s[3] = {3, 3, 3, 4, 4, 4, 3, 3, 3}; s[4] = {4, 4, 4, 4, 4, 4, 4, 4, 4}; t[a_] := Flatten[s /@ a]; p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]]; aa = p[3]
%K nonn,uned
%O 0,3
%A _Roger L. Bagula_, May 27 2005