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

0,3

Links

Table of n, a(n) for n=0..24.

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

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.

Crossrefs

Cf. A383771.

Sequence in context: A081922 A124325 A151248 * A104455 A123952 A005494

Adjacent sequences: A383767 A383768 A383769 * A383771 A383772 A383773

Keyword

nonn

Author

Robert P. Laudone, May 09 2025

Status

approved