A335793 Number of hare pop-stack sortable Cayley permutations.

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

Offset: 0

Author

Michael De Vlieger, Jun 23 2020

Keywords

• nonn
• more

Comments

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

Links

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

Crossrefs

Cf. A000670, A226316.

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)

Extensions

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