A116777 Number of permutations of length n which avoid the patterns 2314, 3142, 4312.

1, 2, 6, 21, 74, 253, 840, 2728, 8719, 27541, 86221, 268047, 828661, 2550116, 7818174, 23893803, 72831350, 221504503, 672394824, 2037817846, 6167472211, 18643839127, 56301766021, 169874621301, 512161584769, 1543128593438

Offset

1,2

Links

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

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (9,-31,52,-45,19,-3)

Formula

G.f.: A(x) = -{(3x^5-12x^4+23x^3-19x^2+7x-1)x}/{(x-1)^3(x^2-3x+1)(3x-1)}

Crossrefs

Sequence in context: A294767 A116827 A116780 * A294768 A116793 A294805

Adjacent sequences: A116774 A116775 A116776 * A116778 A116779 A116780

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved