A116795 Number of permutations of length n which avoid the patterns 2341, 3214, 4123.

1, 2, 6, 21, 70, 212, 611, 1712, 4712, 12815, 34576, 92764, 247819, 659840, 1752170, 4642567, 12278546, 32424408, 85514335, 225286086, 592967054, 1559508979, 4098803122, 10766657412, 28268032251, 74187679124, 194632590500

Offset

1,2

Links

Table of n, a(n) for n=1..27.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 (2017), Table 2 No 18.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (8,-25,40,-37,19,4,-20,18,-7,1).

Formula

G.f.: A(x) = {(x^7-5x^6+8x^5-9x^4+17x^3-15x^2+6x-1)x}/{(x^2+1)(x^3-x^2-2x+1)(x-1)^3(x^2-3x+1)}

Crossrefs

Sequence in context: A294718 A116794 A294719 * A116766 A116825 A116767

Adjacent sequences: A116792 A116793 A116794 * A116796 A116797 A116798

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved