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A140714 Triangle read by rows: T(n,k) is the number of white corners of rank k in all 321-avoiding permutations of {1,2,...,n} (n>=2, 0<=k<=n-2; for definitions see the Eriksson-Linusson references). 0
1, 3, 1, 9, 5, 2, 28, 19, 12, 5, 90, 68, 51, 33, 14, 297, 240, 197, 150, 98, 42, 1001, 847, 735, 609, 466, 306, 132 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

2,2

COMMENTS

Sum of entries in row n is 4^(n-2) (A000302).

T(n,0)=A000245(n-1).

T(n,n-2)=Cat(n-2)=A000108(n-2).

REFERENCES

K. Eriksson and S. Linusson. Combinatorics of Fulton's essential set. Duke Mathematical Journal 85(1):61-76, 1996.

LINKS

Table of n, a(n) for n=2..29.

K. Eriksson and S. Linusson, The size of Fulton's essential set, Electronic J. Combinatorics, Vol. 2, #R6, 1995.

K. Eriksson and S. Linusson, Combinatorics of Fulton's essential set, ResearchGate, 1998.

EXAMPLE

Triangle starts:

1;

3,1;

9,5,2;

28,19,12,5;

90,68,51,33,14;

CROSSREFS

Cf. A000302, A000245, A000108, A140713.

Sequence in context: A112626 A050155 A270236 * A112932 A337680 A077895

Adjacent sequences:  A140711 A140712 A140713 * A140715 A140716 A140717

KEYWORD

nonn,tabl,more

AUTHOR

Emeric Deutsch, May 29 2008

STATUS

approved

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Last modified April 16 00:09 EDT 2021. Contains 343021 sequences. (Running on oeis4.)