OFFSET
1,2
LINKS
Alex Bailey, Martin Finn-Sell, Robert Snocken, Subsemigroup, ideal and congruence growth of free semigroups, arXiv preprint arXiv:1409.2444 [math.GR], 2014.
EXAMPLE
Triangle begins:
1;
2, 8;
3, 37, 113;
4, 145, 1257, 3492;
5, 452, 9020, 67394, 183732;
6, 1374, 60826, 938194, 6398792, 17061118;
7, 3933, 356023, 30492722, 466578957, 3032145644, 7743056064;
...
CROSSREFS
KEYWORD
AUTHOR
N. J. A. Sloane, Apr 03 2015
STATUS
approved