OFFSET
2,2
COMMENTS
The case with 1 diagonal step is A060543.
REFERENCES
Chunwei Song, The Generalized Schroeder Theory, El. J. Combin. 12 (2005) #R53 Theorem 2.1.
FORMULA
T(n,m) = trinomial(m*n+n-2; m*n-2,n-2,2)/(m*n-1) .
EXAMPLE
This is the left-lower portion of the array which starts in row n=2, columns m>=1 as:
1, 2, 3, 4, 5, 6,..
6, 21, 45, 78, 120, 171, 231,.. # A081266
30, 180, 546, 1224, 2310, 3900, 6090, 8976,.. # bisection A055112
140, 1430, 6120, 17710, 40950, 81840, 147630, 246820, 389160,.. # 5-section A034827
630, 10920, 65835, 245700, 695640, 1645020, 3426885, 6497400, ...
2772, 81396, 690690, 3322704, 11515140, 32212719, 77481495, ...
12012, 596904, 7125300, 44170896, 187336380, 619851960, ...
CROSSREFS
KEYWORD
AUTHOR
R. J. Mathar, Nov 08 2010
STATUS
approved