OFFSET
0,19
LINKS
Alois P. Heinz, Antidiagonals n = 0..55, flattened
Wikipedia, Partition of a set
EXAMPLE
A(3,2) = 7: 12|34|56, 12|35|46, 12|36|45, 13|24|56, 14|23|56, 15|26|34, 16|25|34.
Square array A(n,k) begins:
0, 0, 0, 0, 0, 0, ...
1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, ...
1, 1, 7, 28, 103, 376, ...
1, 1, 45, 1063, 22893, 503751, ...
1, 1, 401, 74296, 13080721, 2443061876, ...
MAPLE
A:= proc(n, k) option remember; `if`(k=0, signum(n), add(
(-1)^(n-j+1)*binomial(n, j)*(k*j)!/(j!*k!^j), j=0..n-1))
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