OFFSET
2,3
LINKS
P. J. Cameron, M. Gadouleau, J. D. Mitchell, Y. Peresse, Chains of subsemigroups, arXiv preprint arXiv:1501.06394 [math.GR], 2015. See Table 2.
FORMULA
a(n) = Sum_{k=1..(n-1)} A262294(n,k). - Altug Alkan, Jan 07 2015
EXAMPLE
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 21 2015
EXTENSIONS
New name from Altug Alkan, Jan 05 2016
STATUS
approved