login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A284731 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 123. 2
1, 1, 1, 1, 2, 1, 1, 5, 5, 1, 1, 14, 33, 14, 1, 1, 42, 234, 238, 42, 1, 1, 132, 1706, 4146, 1782, 132, 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, ...

  1,   2,      5,       14,      42,    132, ...

  1,   5,     33,      234,    1706,  12618, ...

  1,  14,    238,     4146,   72152, 126804, ...

  1,  42,   1782,    75187, 3099106, ...

  1, 132,  13593,  1378668, ...

  1, 429, 104756, 25430445, ...

  ...

As a triangular array:

  1,

  1,   1,

  1,   2,    1,

  1,   5,    5,    1,

  1,  14,   33,   14,    1,

  1,  42,  234,  238,   42,   1,

  1, 132, 1706, 4146, 1782, 132, 1,

  ...

CROSSREFS

Cf. A281732, A281733, A281734.

Sequence in context: A139332 A187617 A128612 * A211400 A060854 A091378

Adjacent sequences:  A284728 A284729 A284730 * A284732 A284733 A284734

KEYWORD

nonn,tabl,more

AUTHOR

N. J. A. Sloane, Apr 07 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 25 22:15 EST 2018. Contains 299661 sequences. (Running on oeis4.)