A116742 - OEIS

%I #7 Jul 07 2017 06:31:15

%S 1,2,6,21,75,261,877,2852,9020,27877,84533,252331,743389,2166062,

%T 6252642,17905365,50922495,143958513,404848717,1133309336,3159610856,

%U 8776920517,24301859561,67091484631,184734559165,507443649506

%N Number of permutations of length n which avoid the patterns 1342, 2341, 4132; or avoid the patterns 2431, 3124, 4231.

%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_05">Index entries for linear recurrences with constant coefficients</a>, signature (8,-23,28,-13,2)

%F G.f.: A(x) = -{(2x^4-9x^3+13x^2-6x+1)x}/{(2x-1)(x^2-3x+1)^2}

%K nonn,easy

%O 1,2

%A _Lara Pudwell_, Feb 26 2006