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A284732 Square array read by antidiagonals downwards: T(n,k) = number of linear extensions of the North-East rectangular partial order NE_{n,k} that avoid the pattern 2143. 0
1, 1, 1, 1, 2, 1, 1, 5, 4, 1, 1, 14, 21, 8, 1, 1, 42, 121, 89, 16, 1, 1, 132, 728, 1094, 377, 32, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..28.

David Anderson, E. S. Egge, M. Riehl, L. Ryan, R. Steinke, Y. Vaughan, Pattern Avoiding Linear Extensions of Rectangular Posets, arXiv preprint arXiv:1605.06825 [math.CO], 2016.

EXAMPLE

The square array begins:

  1,  1,   1,    1,      1, ...

  1,  2,   5,   14,     42, ...

  1,  4,  21,  121,    728, ...

  1,  8,  89, 1094,  14041, ...

  1, 16, 377, 9841, 266110, ...

  ...

As a triangular array:

  1,

  1,   1,

  1,   2,   1,

  1,   5,   4,    1,

  1,  14,  21,    8,   1,

  1,  42, 121,   89,  16,  1,

  1, 132, 728, 1094, 377, 32, 1,

  ...

CROSSREFS

Cf. A281731.

For early rows and columns see A000108, A000079 and (apparently) A274969, A015448.

Sequence in context: A241500 A152924 A220738 * A327483 A327884 A050145

Adjacent sequences:  A284729 A284730 A284731 * A284733 A284734 A284735

KEYWORD

nonn,tabl,more

AUTHOR

N. J. A. Sloane, Apr 07 2017

STATUS

approved

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Last modified October 19 09:36 EDT 2021. Contains 348074 sequences. (Running on oeis4.)