A383770 Number of nonnesting permutations of [n] avoiding 231 (and by symmetry 132, 213, or 312).

1, 1, 4, 17, 77, 367, 1815, 9233, 48014, 254123, 1364491, 7414733, 40701346, 225359021, 1257148285, 7058816337, 39863261170, 226270553575, 1290212119208, 7387057794679, 42450966727899, 244771835135261, 1415678529391032, 8210790845555365, 47744558865042855

Offset: 0

Author

Robert P. Laudone, May 09 2025

Keywords

• nonn

Links

• K. Archer and R. P. Laudone, Pattern avoidance in non-crossing and non-nesting permutations, arXiv:2502.13309 [math.CO], 2025.

Crossrefs

Cf. A383771.

Formula

G.f.: A(x) satisfies x^3*A(x)^3 - (x^3+3*x^2+x)*A(x)^2 + (2*x^2-x+1)*A(x) + x - 1 = 0.