A259100 Triangle read by rows, arising in the enumeration of corners.

1, 0, 1, 0, 2, 1, 0, 3, 2, 1, 0, 4, 5, 2, 1, 0, 5, 8, 5, 2, 1, 0, 6, 14, 10, 5, 2, 1, 0, 7, 20, 18, 10, 5, 2, 1, 0, 8, 30, 30, 20, 10, 5, 2, 1

Offset

0,5

Links

Table of n, a(n) for n=0..44.

G. Kreweras, Sur les extensions linéaires d'une famille particuliere d'ordres partiels, Discrete Math., 27 (1979), 279-295.

G. Kreweras, Sur les extensions linéaires d'une famille particulière d'ordres partiels, Discrete Math., 27 (1979), 279-295. (Annotated scanned copy)

Formula

Kreweras gives a recurrence on page 281.

Example

Triangle begins:
  1;
  0,  1;
  0,  2,  1;
  0,  3,  2,  1;
  0,  4,  5,  2,  1;
  0,  5,  8,  5,  2,  1;
  0,  6, 14, 10,  5,  2,  1;
  0,  7, 20, 18, 10,  5,  2,  1;
  0,  8, 30, 30, 20, 10,  5,  2,  1;
  ...

Crossrefs

Row sums = A006330.

Sequence in context: A025653 A131103 A180653 * A368091 A392681 A365004

Adjacent sequences: A259097 A259098 A259099 * A259101 A259102 A259103

Keyword

nonn,tabl,more,changed

Author

N. J. A. Sloane, Jun 22 2015

Status

approved