OFFSET
1,2
LINKS
A. Umar, Combinatorial Results for Semigroups of Orientation-Preserving Partial Transformations, J. Int. Seq. 14 (2011) # 11.7.5, corollary 17, table 2.4, table 2.5.
FORMULA
MAPLE
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Sep 02 2017
STATUS
approved