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Number of permutations of [n] avoiding {1324, 2341, 1243}.
0

%I #6 Mar 21 2021 21:23:52

%S 1,1,2,6,21,76,275,989,3544,12696,45578,164194,593966,2158090,7875503,

%T 28862235,106203597,392291117,1454239837,5409048372,20182045236,

%U 75522431214,283377791271,1065990318403,4019415215923,15188857311110,57514327098488,218201177979480,829305547436095

%N Number of permutations of [n] avoiding {1324, 2341, 1243}.

%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 195.

%p C := (1-sqrt(1-4*x))/2/x ;

%p ((1 -7*x +19*x^2 -25*x^3 +13*x^4 +4*x^5 -5*x^6 +x^7)*C -1 +7*x -19*x^2 +23*x^3 -7*x^4 -7*x^5 +4*x^6)/(x*(1 -x)^2*(1 -3*x +x^2)*(1 -x -x^2));

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

%p gfun[seriestolist](%) ;

%K nonn,easy

%O 0,3

%A _R. J. Mathar_, Nov 09 2017