A079507 Triangle T(n,k) read by rows; related to number of preorders.

1, 1, 4, 4, 1, 15, 63, 96, 48, 1, 44, 468, 1936, 3688, 3264, 1088, 1, 120, 2795, 23990, 98275, 214640, 256720, 158720, 39680

Offset

1,3

Comments

Row n has 2n-1 entries.

Links

Table of n, a(n) for n=1..25.

G. Kreweras, Les préordres totaux compatibles avec un ordre partiel, Math. Sci. Humaines No. 53 (1976), 5-30. (The array on page 22.)

G. Kreweras, Les préordres totaux compatibles avec un ordre partiel, Math. Sci. Humaines No. 53 (1976), 5-30. (Annotated scanned copy)

Formula

How is this array defined?

Example

1; 1,4,4; 1,15,63,96,48; ...

Crossrefs

Sequence in context: A124028 A123966 A371898 * A098364 A116866 A126280

Adjacent sequences: A079504 A079505 A079506 * A079508 A079509 A079510

Keyword

nonn,tabf,more

Author

N. J. A. Sloane, Jan 21 2003

Status

approved