A299789 Number T(n,k) of permutations p of [n] such that min_{j=1..n} |p(j)-j| = k; triangle T(n,k), n >= 0, 0 <= k <= floor(n/2), read by rows.

0, 1, 1, 1, 4, 2, 15, 8, 1, 76, 40, 4, 455, 236, 28, 1, 3186, 1648, 198, 8, 25487, 13125, 1596, 111, 1, 229384, 117794, 14534, 1152, 16, 2293839, 1175224, 146372, 12929, 435, 1, 25232230, 12903874, 1621282, 152430, 6952, 32, 302786759, 154615096, 19563257, 1922364, 112416, 1707, 1

Offset: 0

Author

Alois P. Heinz, Jan 21 2019

Keywords

• nonn
• tabf

Examples

			T(4,0) = 15: 1234, 1243, 1324, 1342, 1423, 1432, 2134, 2314, 2431, 3124, 3214, 3241, 4132, 4213, 4231.
T(4,1) = 8: 2143, 2341, 2413, 3142, 3421, 4123, 4312, 4321.
T(4,2) = 1: 3412.
T(5,2) = 4: 34512, 34521, 45123, 54123.
T(6,3) = 1: 456123.
T(7,3) = 8: 4567123, 4567132, 4567213, 4567231, 5671234, 5761234, 6571234, 7561234.
T(8,4) = 1: 56781234.
T(9,4) = 16: 567891234, 567891243, 567891324, 567891342, 567892134, 567892143, 567892314, 567892341, 678912345, 679812345, 687912345, 697812345, 768912345, 769812345, 867912345, 967812345.
Triangle T(n,k) begins:
          0;
          1;
          1,         1;
          4,         2;
         15,         8,        1;
         76,        40,        4;
        455,       236,       28,       1;
       3186,      1648,      198,       8;
      25487,     13125,     1596,     111,      1;
     229384,    117794,    14534,    1152,     16;
    2293839,   1175224,   146372,   12929,    435,    1;
   25232230,  12903874,  1621282,  152430,   6952,   32;
  302786759, 154615096, 19563257, 1922364, 112416, 1707, 1;
  ...
		

Links

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

Crossrefs

Columns k=0-1 give: A002467, A296050.

Row sums give A000142 (for n>0).

T(2n,n) gives A057427.

T(2n+1,n) gives A000079.

T(2n+2,n) gives A306545.

Cf. A000166, A001883, A075851, A075852, A129118, A130152, A306543.

Programs

Maple

b:= proc(s) option remember; (n-> `if`(n=1, x^(s[1]-1),
      add((p-> add(coeff(p, x, i)*x^min(i, abs(n-j)),
      i=0..degree(p)))(b(s minus {j})), j=s)))(nops(s))
    end:
T:= n-> (p-> seq(coeff(p, x, i), i=0..max(0, degree(p))))(b({$1..n})):
seq(T(n), n=0..14);
# second Maple program:
A:= proc(n, k) option remember; `if`(n=0, 0, LinearAlgebra[
      Permanent](Matrix(n, (i, j)-> `if`(abs(i-j)>=k, 1, 0))))
    end:
T:= (n, k)-> A(n, k)-A(n, k+1):
seq(seq(T(n, k), k=0..n/2), n=0..14);

Mathematica

A[n_, k_] := A[n, k] = If[n==0, 0, Permanent[Table[If[Abs[i-j] >= k, 1, 0], {i, 1, n}, {j, 1, n}]]];
T[n_, k_] := A[n, k] - A[n, k+1];
Table[T[n, k], {n, 0, 14}, {k, 0, n/2}] // Flatten (* Jean-François Alcover, May 01 2019, from 2nd Maple program *)

Formula

T(n,k) = A306543(n,k) - A306543(n,k+1) for n > 0.

Sum_{k=1..floor(n/2)} k * T(n,k) = A129118(n).

Sum_{k=1..floor(n/2)} T(n,k) = A000166(n).

Sum_{k=2..floor(n/2)} T(n,k) = A001883(n).

Sum_{k=3..floor(n/2)} T(n,k) = A075851(n).

Sum_{k=4..floor(n/2)} T(n,k) = A075852(n).