A116741 Number of permutations of length n which avoid the patterns 1342, 2314, 4213.

1, 2, 6, 21, 73, 241, 757, 2288, 6724, 19365, 54959, 154303, 429733, 1189430, 3276306, 8990037, 24591349, 67093357, 182653717, 496322396, 1346450176, 3647459397, 9868036571, 26666447611, 71984395333, 194127819746

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 95.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (10,-40,82,-92,56,-17,2).

Formula

G.f.: A(x) = -{(2x^6-13x^5+31x^4-41x^3+26x^2-8x+1)x}/{(2x-1)(x^2-3x+1)^2(x-1)^2}

Crossrefs

Sequence in context: A116787 A294803 A116773 * A116843 A116822 A116797

Adjacent sequences: A116738 A116739 A116740 * A116742 A116743 A116744

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved