A140713 -id:A140713 - cp's OEIS frontend

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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).

Original entry on oeis.org

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

Offset: 2

Emeric Deutsch, May 29 2008

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).

			Triangle starts:
1;
3,1;
9,5,2;
28,19,12,5;
90,68,51,33,14;

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

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.

Cf. A000302, A000245, A000108, A140713.

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