A116808 Number of permutations of length n which avoid the patterns 1342, 3214, 4312.

1, 2, 6, 21, 71, 213, 569, 1389, 3175, 6927, 14632, 30238, 61596, 124335, 249598, 499492, 997953, 1992420, 3977093, 7939304, 15852025, 31658506, 63240940, 126356805, 252509950, 504690182, 1008848258, 2016839103, 4032297299

Offset

1,2

Links

Table of n, a(n) for n=1..29.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 (2017), Table 2 No 27.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (9,-34,69,-78,41,6,-21,11,-2).

Formula

G.f.: A(x) = -{(5x^8-12x^7+3x^6+11x^5-26x^4+34x^3-22x^2+7x-1)x}/{(2x-1)(x-1)^6(x^2-1+x)}

Crossrefs

Sequence in context: A294725 A116755 A116833 * A294726 A294700 A294701

Adjacent sequences: A116805 A116806 A116807 * A116809 A116810 A116811

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved