A116752 Number of permutations of length n which avoid the patterns 1234, 1342, 2431.

1, 2, 6, 21, 74, 248, 787, 2389, 7013, 20079, 56417, 156250, 427914, 1161571, 3130892, 8391305, 22387648, 59509600, 157714833, 416978205, 1100298811, 2898861767, 7627745311, 20050436226, 52661977424, 138224905323

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 120.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (11,-51,130,-199,187,-105,32,-4)

Formula

G.f.: A(x) = -{x(5x^7-28x^6+64x^5-88x^4+73x^3-35x^2+9x-1)}/{(2x-1)^2(x-1)^4(x^2-3x+1)}

Crossrefs

Sequence in context: A116831 A294698 A294766 * A294767 A116827 A116780

Adjacent sequences: A116749 A116750 A116751 * A116753 A116754 A116755

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved