OFFSET
0,3
LINKS
Robert Israel, Table of n, a(n) for n = 0..10000
A. Cobham, On the Hartmanis-Stearns problem for a class of tag machines, 9th Annual Symposium on Switching and Automata Theory (SWAT 1968)(FOCS), pp. 51-60, 1968; doi:10.1109/SWAT.1968.20. See Example 7.
MAPLE
f(0):= (0, 1):
f(1):= (2, 1):
f(2):= (1, 3):
f(3):= (3, 3):
A:= [0]:
for i from 1 to 8 do A:= map(f, A) od:
A; # Robert Israel, Jul 18 2018
MATHEMATICA
Nest[ Flatten[# /. {0 -> {0, 1}, 1 -> {2, 1}, 2 -> {1, 3}, 3 -> {3, 3}}] &, {0}, 7] (* Robert G. Wilson v, Jul 18 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 18 2018
STATUS
approved