%I A105646
%S A105646 1,2,1,3,4,3,1,2,1,4,3,4,2,1,2,4,3,4,1,2,1,3,4,3,1,2,1,2,1,2,4,3,4,2,1,
%T A105646 2,3,4,3,1,2,1,3,4,3,2,1,2,4,3,4,2,1,2,1,2,1,3,4,3,1,2,1,4,3,4,2,1,2,4,
%U A105646 3,4,1,2,1,3,4,3,1,2,1,3,4,3,1,2,1,3,4,3,2,1,2,4,3,4,2,1,2,3,4,3,1,2,1
%N A105646 Fixed point of the morphism 1 -> 121, 2 -> 343, 3 -> 434, 4 -> 212, starting 
               from a(0) = 1.
%C A105646 Rectangular space-fill from Peano space-fill by row permutation of the 
               digraph matrix: Characteristic polynomial: x^4-3*x^3-3*x+9.
%D A105646 F. M. Deking, "Recurrent Sets", Advances in Mathematics, vol. 44, no. 
               1, 1982, page 85, section 4.1
%F A105646 1->{1, 2, 1}, 2->{3, 4, 3}, 3->{4, 3, 4}, 4->{2, 1, 2}
%t A105646 Flatten[ Nest[ Flatten[ # /. {1 -> {1, 2, 1}, 2 -> {3, 4, 3}, 3 -> {4, 
               3, 4}, 4 -> {2, 1, 2}}] &, {1}, 4]] (* Robert G. Wilson v *)
%Y A105646 Sequence in context: A026366 A122164 A076632 this_sequence A059126 A059128 
               A050273
%Y A105646 Adjacent sequences: A105643 A105644 A105645 this_sequence A105647 A105648 
               A105649
%K A105646 nonn
%O A105646 0,2
%A A105646 Roger Bagula (rlbagulatftn(AT)yahoo.com), May 03 2005
%E A105646 Edited by Robert G. Wilson v (rgwv(at)rgwv.com), Jan 24 2006