A116736 Number of permutations of length n which avoid the patterns 1432, 2314, 2413.

1, 2, 6, 21, 75, 263, 904, 3066, 10324, 34652, 116179, 389443, 1305592, 4377595, 14679474, 49227937, 165091510, 553658600, 1856778673, 6226985606, 20883103968, 70034469898, 234870470627, 787671056978, 2641565114181

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 167.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (7,-17,18,-7,1)

Formula

G.f.: A(x) = -{(x^4-5x^3+9x^2-5x+1)x}/{(x^5-7x^4+18x^3-17x^2+7x-1)}

Crossrefs

Sequence in context: A116742 A116746 A116806 * A116820 A369626 A294815

Adjacent sequences: A116733 A116734 A116735 * A116737 A116738 A116739

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved