A116806 Number of permutations of length n which avoid the patterns 2314, 4213, 4312.

1, 2, 6, 21, 75, 262, 891, 2964, 9700, 31374, 100639, 320949, 1019396, 3228687, 10206180, 32219494, 101619194, 320303001, 1009163739, 3178610330, 10009874543, 31518335944, 99233864812, 312414443206, 983524845979

Offset

1,2

Links

Table of n, a(n) for n=1..25.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 [math.CO] (2017), Table 2 No 161.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (9,-31,52,-45,20,-4).

Formula

G.f.: A(x) = -{x(4x^5-13x^4+23x^3-19x^2+7x-1)}/{(2x-1)^2(x-1)(-1+4x-3x^2+x^3)}

Crossrefs

Sequence in context: A116816 A116742 A116746 * A116736 A116820 A369626

Adjacent sequences: A116803 A116804 A116805 * A116807 A116808 A116809

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved