A116841 Number of permutations of length n which avoid the patterns 1234, 1324, 2431.

1, 2, 6, 21, 75, 258, 842, 2614, 7787, 22466, 63273, 175044, 477897, 1291997, 3467411, 9254394, 24595834, 65158141, 172181087, 454099591, 1195773446, 3144999057, 8263735626, 21697177681, 56933687000, 149323655848

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 147.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (13,-73,231,-448,534,-349,43,119,-97,32,-4).

Formula

G.f.: -(4x^10 -19x^9 +52x^8 -36x^7 -81x^6 +208x^5 -226x^4 +142x^3 -53x^2 +11x -1)*x/((2x-1)^2 (x-1)^5 (x^2-1+x) (x^2-3x+1)).

Crossrefs

Sequence in context: A294770 A116763 A116840 * A116814 A294806 A294807

Adjacent sequences: A116838 A116839 A116840 * A116842 A116843 A116844

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved