A289597 Related to number of mesh patterns of length 2 that avoid the pattern 321.

1, 1, 1, 2, 6, 21, 75, 266, 938, 3305, 11679

Offset

1,4

Links

Table of n, a(n) for n=1..11.

Murray Tannock, Equivalence classes of mesh patterns with a dominating pattern, MSc Thesis, Reykjavik Univ., May 2016. See Appendix B2.

Murray Tannock, Henning Ulfarsson, Equivalence classes of mesh patterns with a dominating pattern, arXiv:1704.07104 [math.CO], 2017-2018.

Formula

G.f.: x*(1-x)*C(x) + x^2*(x^2-3*x+1)/((x-1)*(2*x-1)) (conjectured), where C(x) is the g.f. for the Catalan numbers (A000108). - Michael D. Weiner, Jan 02 2019

Crossrefs

Cf. A000108.

Sequence in context: A294815 A116751 A116823 * A116743 A294816 A263790

Adjacent sequences: A289594 A289595 A289596 * A289598 A289599 A289600

Keyword

nonn,more

Author

N. J. A. Sloane, Jul 08 2017

Status

approved