A335793 Number of hare pop-stack sortable Cayley permutations.

1, 1, 3, 11, 41, 151, 553, 2023, 7401

Offset

0,3

Comments

Also, the set of Cayley permutations avoiding 231, 312, and 2121.

Links

Table of n, a(n) for n=0..8.

Giulio Cerbai, Sorting Cayley permutations with pattern-avoiding machines, arXiv:2003.02536 [math.CO], 2020. See p. 16.

Formula

Conjectures from Colin Barker, Jun 24 2020: (Start)

G.f.: (1 - 4*x + 4*x^2 - 2*x^3) / (1 - 5*x + 6*x^2 - 4*x^3).

a(n) = 5*a(n-1) - 6*a(n-2) + 4*a(n-3) for n>3.

(End)

Crossrefs

Cf. A000670, A226316.

Sequence in context: A086972 A218348 A320827 * A077831 A032952 A001835

Adjacent sequences: A335790 A335791 A335792 * A335794 A335795 A335796

Keyword

nonn,more

Author

Michael De Vlieger, Jun 23 2020

Extensions

a(7)-a(8) from Giulio Cerbai via Michael De Vlieger, Jun 24 2020

Status

approved