A116827 Number of permutations of length n which avoid the patterns 1234, 1342, 4132.

1, 2, 6, 21, 74, 249, 798, 2459, 7351, 21457, 61434, 173120, 481461, 1324409, 3610321, 9768290, 26267339, 70277944, 187252097, 497243636, 1316797076, 3479358732, 9176849481, 24168624981, 63576482894, 167080909424

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 123.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (12,-62,181,-329,386,-292,137,-36,4).

Formula

G.f.: A(x) = -{(4x^8-33x^7+91x^6-151x^5+161x^4-108x^3+44x^2-10x+1)x}/{(x-1)^5(2x-1)^2(x^2-3x+1)}

Crossrefs

Sequence in context: A294766 A116752 A294767 * A116780 A116777 A294768

Adjacent sequences: A116824 A116825 A116826 * A116828 A116829 A116830

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved