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Number of permutations of [n] avoiding {1324, 2314, 2431}.
0

%I #8 Mar 21 2021 21:38:43

%S 1,1,2,6,21,76,271,938,3146,10252,32583,101368,309697,931708,2766374,

%T 8121630,23612985,68076148,194824915,553979438,1566301826,4406286736,

%U 12340335627,34422720496,95676632581,265071811456,732238423646,2017390937058,5544712079421,15205817438572

%N Number of permutations of [n] avoiding {1324, 2314, 2431}.

%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 [math.CO] (2017), Table 1 No 187.

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (10,-39,74,-69,28,-4).

%p (1 -9*x +31*x^2 -49*x^3 +34*x^4 -7*x^5)/((1 -3*x +x^2)^2*(1 -2*x)^2) ;

%p taylor(%,x=0,40) ;

%p gfun[seriestolist](%) ;

%K nonn,easy

%O 0,3

%A _R. J. Mathar_, Nov 09 2017