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A289451
Related to number of mesh patterns of length 2 that avoid the pattern 231.
0
1, 1, 1, 2, 8, 32, 117, 408, 1402, 4826, 16751
OFFSET
1,4
LINKS
Murray Tannock, Equivalence classes of mesh patterns with a dominating pattern, MSc Thesis, Reykjavik Univ., May 2016. See Appendix B1.
FORMULA
Conjectures from Vladimir Kruchinin, Jan 06 2022: (Start)
a(n) = binomial(2*n,n)/(n+1) - (n-1)*n/2.
G.f.: (1-sqrt(1-4*x))/(2*x) - x^2/((1-x))^3. (End)
CROSSREFS
Sequence in context: A067897 A145682 A363109 * A230509 A099752 A230393
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Jul 08 2017
STATUS
approved