A262494 Triangle read by rows: T(n,k) (n>=1, 0<=k

1, 1, 1, 1, 4, 1, 1, 13, 8, 2, 1, 41, 49, 23, 6, 1, 131, 276, 198, 90, 24, 1, 428, 1509, 1556, 982, 444, 120, 1, 1429, 8184, 11812, 9678, 5856, 2640, 720, 1, 4861, 44473, 88566, 91959, 68820, 40800, 18360, 5040, 1, 16795, 243334, 662732, 863296, 775134, 555828, 325200, 146160, 40320

Offset: 1

Author

Christian Stump, Sep 24 2015

Keywords

• nonn
• tabl

Comments

It appears that no recurrence or g.f. is known. - N. J. A. Sloane, Oct 13 2015

Examples

			Triangle begins:
  1;
  1,    1;
  1,    4,     1;
  1,   13,     8,     2;
  1,   41,    49,    23,     6;
  1,  131,   276,   198,    90,    24;
  1,  428,  1509,  1556,   982,   444,   120;
  1, 1429,  8184, 11812,  9678,  5856,  2640,   720;
  1, 4861, 44473, 88566, 91959, 68820, 40800, 18360, 5040;
  ...
		

Links

• FindStat - Combinatorial Statistic Finder, The number of stack-sorts needed to sort a permutation
• Julian West, Permutations with forbidden subsequences; and, stack-sortable permutations, Ph.D. thesis, Massachusetts Institute of Technology, Dept. of Mathematics, 1990. See p. 76.

Crossrefs

Columns k=0-1 give: A000012, A001453.

Row sums give A000142.

Cf. A000108.

Formula

T(n,0) = 1, T(n,1) = A000108(n) - 1. - Joerg Arndt, Sep 27 2015

Extensions

Definition edited by N. J. A. Sloane, Oct 13 2015

More terms from Christian Stump, Oct 19 2015

Rows n=7-10 from Julian West's thesis added by Alois P. Heinz, Jun 27 2023