OFFSET
1,4
COMMENTS
T(n,k) is equivalent to n! minus the number of permutations on n elements with zero k-cycles (sequence A122974).
LINKS
Dennis P. Walsh, The number of permutations with no k-cycles
FORMULA
T(n,k) = n! * Sum_{j=1..floor(n/k)} (-1)^(j+1)*(1/k)^j/j!.
T(n,k) = n! - A122974(n,k).
E.g.f. of column k: (1-exp(-x^k/k))/(1-x). - Alois P. Heinz, Oct 11 2017
EXAMPLE
T(n,k) (the first 8 rows):
: 1;
: 1, 1;
: 4, 3, 2;
: 15, 9, 8, 6;
: 76, 45, 40, 30, 24;
: 455, 285, 200, 180, 144, 120;
: 3186, 1995, 1400, 1260, 1008, 840, 720;
: 25487, 15855, 11200, 8820, 8064, 6720, 5760, 5040;
...
T(4,3)=8 since there are exactly 8 permutations on {1,2,3,4} with at least one 3-cycle: (1)(234), (1)(243), (2)(134), (2)(143), (3)(124), (3)(142), (4)(123), and (4)(132).
MAPLE
T:=(n, k)->n!*sum((-1)^(j+1)*(1/k)^j/j!, j=1..floor(n/k)); seq(seq(T(n, k), k=1..n), n=1..10);
MATHEMATICA
Table[n!*Sum[(-1)^(j + 1)*(1/k)^j/j!, {j, Floor[n/k]}], {n, 10}, {k, n}] // Flatten (* Michael De Vlieger, Oct 02 2017 *)
CROSSREFS
KEYWORD
AUTHOR
Dennis P. Walsh, Oct 02 2017
STATUS
approved