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
Keywords
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.