OFFSET
0,13
LINKS
Alois P. Heinz, Antidiagonals n = 0..54, flattened
Wikipedia, Partition of a set
EXAMPLE
A(2,3) = 9: 124|356, 125|346, 126|345, 134|256, 135|246, 136|245, 145|236, 146|235, 156|234.
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, ...
0, 0, 0, 0, 0, 0, ...
0, 0, 2, 9, 34, 125, ...
0, 0, 8, 252, 5672, 125750, ...
0, 0, 60, 14337, 2604732, 488360625, ...
0, 0, 544, 1327104, 2533087904, 5192229797500, ...
MAPLE
A:= proc(n, k) `if`(k=0, `if`(n=0, 1, 0), add(
(-1)^(n-j)*binomial(n, j)*(k*j)!/(j!*k!^j), j=0..n))
end:
seq(seq(A(n, d-n), n=0..d), d=0..10);
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Feb 16 2024
STATUS
approved