OFFSET
0,3
MATHEMATICA
Nest[ Function[ l, {Flatten[(l /. {0 -> {0, 1}, 1 -> {2, 0}, 2 -> {2, 0}})]}], {0}, 7] (* Robert G. Wilson v, Feb 28 2005 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Dec 11 2004
STATUS
approved