A161746 The number of equivalence classes of n-leaf binary trees with respect to contiguous pattern avoidance.

1, 1, 1, 2, 3, 7, 15, 43, 136

Offset: 1

Author

Eric Rowland, Jun 17 2009

Keywords

• nonn
• hard
• more

Examples

			Representatives of the a(6) = 7 equivalence classes of 6-leaf binary trees are given in A036766, A159768, A159769, A159770, A159771, A159772, and A159773.
		

Links

• Andrey T. Cherkasov and Dmitri Piontkovski, Wilf classes of non-symmetric operads, arXiv:2105.08880 [math.CO], 2021.
• L. Pudwell, Pattern avoidance in trees, (slides from a talk, mentions many sequences), 2012. - _N. J. A. Sloane_, Jan 03 2013
• Eric S. Rowland, Pattern avoidance in binary trees, arXiv:0809.0488 [math.CO], 2008-2010.
• Eric S. Rowland, Pattern avoidance in binary trees, J. Comb. Theory A 117 (6) (2010) 741-758.

Crossrefs

Cf. A099952.

Extensions

Per Cherkasov and Piontkovski, a(8) corrected by Eric Rowland, May 22 2021

a(9) from Eric Rowland, Apr 25 2024