A374985 Array read by antidiagonals: T(n,k) is the number of n X k matrices whose values cover an initial interval of positive integers and whose rows and columns have values which are strictly increasing.
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 11, 11, 1, 1, 1, 1, 45, 197, 45, 1, 1, 1, 1, 197, 4593, 4593, 197, 1, 1, 1, 1, 903, 126289, 732963, 126289, 903, 1, 1, 1, 1, 4279, 3888343, 155242003, 155242003, 3888343, 4279, 1, 1, 1, 1, 20793, 130016393, 40007492715, 289599115433, 40007492715, 130016393, 20793, 1, 1
Offset: 0
Examples
Array begins: ===================================================================== n/k | 0 1 2 3 4 5 6 ... ----+---------------------------------------------------------------- 0 | 1 1 1 1 1 1 1 ... 1 | 1 1 1 1 1 1 1 ... 2 | 1 1 3 11 45 197 903 ... 3 | 1 1 11 197 4593 126289 3888343 ... 4 | 1 1 45 4593 732963 155242003 40007492715 ... 5 | 1 1 197 126289 155242003 289599115433 723253222084867 ... 6 | 1 1 903 3888343 40007492715 723253222084867 ... ... The T(2,3) = 11 matrices are: [1 2 3] [1 2 3] [1 2 3] [1 2 3] [1 2 4] [1 2 4] [2 3 4] [2 4 5] [3 4 5] [4 5 6] [2 3 5] [3 4 5] . [1 2 4] [1 2 5] [1 3 4] [1 3 4] [1 3 5] [3 5 6] [3 4 6] [2 4 5] [2 5 6] [2 4 6]
Links
- Andrew Howroyd, Table of n, a(n) for n = 0..230
- R. A. Sulanke, Generalizing Narayana and Schroeder Numbers to Higher Dimensions, Electron. J. Combin. 11 (2004), Research Paper 54.
Crossrefs
Programs
Formula
T(n,k) = T(k,n).
Comments