OFFSET
1,1
COMMENTS
EXAMPLE
For n = 2, where the permutations are 12 and 21, the six possible 2-tuples are (0,0) (corresponding to the empty string); (1,0) (corresponding to 1); (0,1) (corresponding to 2); (2,1) (corresponding to 12); (1,2) (corresponding to 21); (2,2) (corresponding to 121).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jeffrey Shallit, Jun 30 2015
STATUS
approved