A116790 Number of permutations of length n which avoid the patterns 1423, 1432, 3241.

1, 2, 6, 21, 74, 256, 880, 3025, 10406, 35805, 123197, 423881, 1458425, 5017929, 17264954, 59402739, 204384285, 703215622, 2419521666, 8324736993, 28642540011, 98549071193, 339073260558, 1166633785846, 4013983255478

Offset

1,2

Links

Table of n, a(n) for n=1..25.

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 136.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (5,-7,6,-1,-1).

Formula

G.f.: A(x) = -{x(x-1)^3}/{1-6x^3+x^4+x^5-5x+7x^2}

Crossrefs

Sequence in context: A116793 A294805 A116805 * A116817 A116764 A294769

Adjacent sequences: A116787 A116788 A116789 * A116791 A116792 A116793

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved