OFFSET
1,2
COMMENTS
Row sums are A221882.
REFERENCES
A. D. Adeshola, V. Maltcev and A. Umar, Combinatorial results for certain semigroups of order-preserving full contraction mappings of a finite chain, (submitted).
FORMULA
T(n,1) = n and T(n,k) = 2(n-k+1)*C(n-1,k-1) if k > 1.
EXAMPLE
T (3,2) = 8 because there are exactly 8 order-preserving full contraction mappings (of a 3-chain) with exactly height 2, namely: (112), (122), (211), (221), (223), (233), (322), (332).
CROSSREFS
KEYWORD
nonn
AUTHOR
Abdullahi Umar, Feb 28 2013
STATUS
approved