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%I #9 Nov 08 2017 07:46:37
%S 1,2,6,21,73,233,677,1819,4606,11171,26274,60471,137059,307245,683171,
%T 1509595,3319028,7266583,15850872,34462295,74700801,161470161,
%U 348116785,748673435,1606409882,3439322827,7348417246,15669920663,33353112015
%N Number of permutations of length n which avoid the patterns 2134, 3421, 4231.
%H D. Callan, T. Mansour, <a href="http://arxiv.org/abs/1705.00933">Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns</a>, arXiv:1705.00933 (2017), Table 2 No 67.
%H Lara Pudwell, <a href="http://faculty.valpo.edu/lpudwell/maple/webbook/bookmain.html">Systematic Studies in Pattern Avoidance</a>, 2005.
%H <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (12,-63,190,-363,456,-377,198,-60,8).
%F 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}
%K nonn,easy
%O 1,2
%A _Lara Pudwell_, Feb 26 2006