A116753 Number of permutations of length n which avoid the patterns 2134, 3241, 4312.

1, 2, 6, 21, 73, 236, 705, 1970, 5224, 13307, 32866, 79251, 187523, 437030, 1005935, 2291536, 5174458, 11596189, 25816552, 57141641, 125822061, 275766912, 601872301, 1308610526, 2835334908, 6123666671, 13186871710, 28319917295

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 70.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (11,-52,138,-225,231,-146,52,-8).

Formula

G.f.: A(x) = -{x(8x^7-41x^6+84x^5-103x^4+79x^3-36x^2+9x-1)}/{(2x-1)^3(x-1)^5}

Crossrefs

Sequence in context: A116739 A116770 A294796 * A294762 A294797 A294763

Adjacent sequences: A116750 A116751 A116752 * A116754 A116755 A116756

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved