A116739 Number of permutations of length n which avoid the patterns 2134, 3421, 4231.

1, 2, 6, 21, 73, 233, 677, 1819, 4606, 11171, 26274, 60471, 137059, 307245, 683171, 1509595, 3319028, 7266583, 15850872, 34462295, 74700801, 161470161, 348116785, 748673435, 1606409882, 3439322827, 7348417246, 15669920663, 33353112015

Offset

1,2

Links

Table of n, a(n) for n=1..29.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 (2017), Table 2 No 67.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (12,-63,190,-363,456,-377,198,-60,8).

Formula

G.f.: A(x) = {x(2x^9-8x^8+53x^7-133x^6+190x^5-182x^4+115x^3-45x^2+10x-1)}/{(2x-1)^3(x-1)^6}

Crossrefs

Sequence in context: A116824 A116789 A116783 * A116770 A294796 A116753

Adjacent sequences: A116736 A116737 A116738 * A116740 A116741 A116742

Keyword

nonn,easy

Author

Lara Pudwell, Feb 26 2006

Status

approved