A116787 Number of permutations of length n which avoid the patterns 1432, 2314, 3124.

1, 2, 6, 21, 73, 240, 759, 2365, 7369, 23069, 72495, 228186, 718341, 2260566, 7111650, 22370236, 70367607, 221357774, 696358788, 2190680327, 6891703804, 21680712093, 68205549672, 214568342539, 675012376279, 2123528489810

Offset

1,2

Links

Table of n, a(n) for n=1..26.

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 92.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (8,-25,40,-32,7,4,-6,2,-1).

Formula

G.f.: A(x) = -{x(x^8-x^7+2x^6+2x^5-7x^4+17x^3-15x^2+6x-1)}/{x^9-2x^8+6x^7-4x^6-7x^5+32x^4-40x^3+25x^2-8x+1}

Crossrefs

Sequence in context: A116788 A294695 A116778 * A294803 A116773 A116741

Adjacent sequences: A116784 A116785 A116786 * A116788 A116789 A116790

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved