A116791 - OEIS

%I #10 Nov 08 2017 05:44:32

%S 1,2,6,21,72,220,590,1409,3055,6118,11474,20373,34542,56304,88714,

%T 135713,202301,294730,420718,589685,813012,1104324,1479798,1958497,

%U 2562731,3318446,4255642,5408821,6817466,8526552

%N Number of permutations of length n which avoid the patterns 1234, 1342, 4312.

%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 41.

%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_08">Index entries for linear recurrences with constant coefficients</a>, signature (8,-28,56,-70,56,-28,8,-1).

%F G.f.: A(x) = -{(x^7-6x^6+20x^5-30x^4+27x^3-18x^2+6x-1)x}/{(x-1)^8}

%F a(n) = (n^7 + 35n^6 - 203n^5 + 665n^4 - 686n^3 + 1820n^2 - 1632n + 5040)/5040. - Franklin T. Adams-Watters, Sep 16 2006

%K nonn,easy

%O 1,2

%A _Lara Pudwell_, Feb 26 2006