A116835 Number of permutations of length n which avoid the patterns 1234, 2431, 4132.

1, 2, 6, 21, 71, 209, 545, 1348, 3270, 7908, 19201, 46918, 115407, 285642, 711031, 1779289, 4474537, 11304830, 28685778, 73083753, 186888321, 479511547, 1234006566, 3184091383, 8234890726, 21340207949, 55396690600, 144013075958

Offset

1,2

Links

Table of n, a(n) for n=1..28.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 (2017), Table 2 No 23

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (14,-86,305,-691,1044,-1064,721,-310,76,-8).

Formula

G.f.: x* (24x^13 -188x^12 +585x^11 -913x^10 +688x^9 -88x^8 -309x^7 +442x^6 -471x^5 +374x^4 -196x^3 +64x^2 -12x+1)/((2x-1)^3 (x-1)^5 (x^2-3x+1))

Crossrefs

Sequence in context: A116825 A116767 A116759 * A294725 A116755 A116833

Adjacent sequences: A116832 A116833 A116834 * A116836 A116837 A116838

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved