A Latin rectangle is a
matrix with elements
such that entries
in each row and column are distinct. If
, the special case of a Latin
square results. A normalized Latin rectangle has first row
and first column
. Let
be the number of normalized
Latin rectangles, then the total number of
Latin rectangles is
(1)
|
(McKay and Rogoyski 1995), where is a factorial. Kerewala (1941)
found a recurrence relation for
, and Athreya et al. (1980) found a summation formula for
.
The asymptotic value of was found by Godsil and McKay (1990). The numbers
of
Latin rectangles are given in the following table from McKay and Rogoyski (1995).
The entries
and
are omitted, since
(2)
| |||
(3)
|
but
and
are included for clarity. The values of
are given as a "wrap-around" series by OEIS
A001009.
1 | 1 | 1 |
2 | 1 | 1 |
3 | 2 | 1 |
4 | 2 | 3 |
4 | 3 | 4 |
5 | 2 | 11 |
5 | 3 | 46 |
5 | 4 | 56 |
6 | 2 | 53 |
6 | 3 | 1064 |
6 | 4 | 6552 |
6 | 5 | 9408 |
7 | 2 | 309 |
7 | 3 | 35792 |
7 | 4 | 1293216 |
7 | 5 | 11270400 |
7 | 6 | 16942080 |
8 | 2 | 2119 |
8 | 3 | 1673792 |
8 | 4 | 420909504 |
8 | 5 | 27206658048 |
8 | 6 | 335390189568 |
8 | 7 | 535281401856 |
9 | 2 | 16687 |
9 | 3 | 103443808 |
9 | 4 | 207624560256 |
9 | 5 | 112681643083776 |
9 | 6 | 12952605404381184 |
9 | 7 | 224382967916691456 |
9 | 8 | 377597570964258816 |
10 | 2 | 148329 |
10 | 3 | 8154999232 |
10 | 4 | 147174521059584 |
10 | 5 | 746988383076286464 |
10 | 6 | 870735405591003709440 |
10 | 7 | 177144296983054185922560 |
10 | 8 | 4292039421591854273003520 |
10 | 9 | 7580721483160132811489280 |