A368401 Number T(n,k) of permutations of [n] whose sum of cycle maxima minus cycle minima gives k, triangle T(n,k), n>=0, 0<=k<=A002620(n), read by rows.

1, 1, 1, 1, 1, 2, 3, 1, 3, 7, 11, 2, 1, 4, 12, 28, 53, 12, 10, 1, 5, 18, 52, 135, 289, 84, 72, 58, 6, 1, 6, 25, 84, 257, 734, 1825, 524, 564, 496, 422, 60, 42, 1, 7, 33, 125, 429, 1407, 4545, 12983, 3520, 3976, 4292, 3950, 3422, 790, 486, 330, 24

Offset: 0

Author

Alois P. Heinz, Dec 22 2023

Keywords

• nonn
• look
• tabf

Examples

			T(3,0) = 1: (1)(2)(3).
T(3,1) = 2: (12)(3), (1)(23).
T(3,2) = 3: (123), (132), (13)(2).
Triangle T(n,k) begins:
  1;
  1;
  1, 1;
  1, 2,  3;
  1, 3,  7, 11,   2;
  1, 4, 12, 28,  53,  12,   10;
  1, 5, 18, 52, 135, 289,   84,  72,  58,   6;
  1, 6, 25, 84, 257, 734, 1825, 524, 564, 496, 422, 60, 42;
  ...
		

Links

• Alois P. Heinz, Rows n = 0..21, flattened
• Wikipedia, Permutation

Crossrefs

Row sums give A000142.

Cf. A002538, A002620, A124327, A143946, A367955, A368338.

Programs

Maple

b:= proc(n, s) option remember; `if`(n=0, 1, (k-> `if`(n>k,
      b(n-1, s)+add(b(n-1, subs(h=h+[0, 1], s)), h=s), 0)+
      `if`(n>k+1, b(n-1, {s[], [n,1]}), 0)+add(h[2]!*expand(
      x^(h[1]-n)*b(n-1, s minus {h})), h=s))(nops(s)))
    end:
T:= (n, k)-> coeff(b(n, {}), x, k):
seq(seq(T(n, k), k=0..floor(n^2/4)), n=0..10);

Formula

Sum_{k=0..A002620(n)} k * T(n,k) = A002538(n-1) for n >= 1.