OFFSET
0,2
MATHEMATICA
SubstitutionSystem[{1 -> {1, 2, 3, 4, 1, 1}, 2 -> {2, 1, 4, 3, 2, 2}, 3 -> {3, 4, 1, 2, 3, 3}, 4 -> {4, 3, 2, 1, 4, 4}}, {1}, {3}] // Flatten
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Robert P. P. McKone, Jul 17 2024
STATUS
approved