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%I #6 Mar 21 2021 21:16:38
%S 1,1,2,6,21,75,265,927,3229,11253,39355,138362,489440,1742576,6244395,
%T 22516585,81673947,297894234,1092086024,4022418903,14879231036,
%U 55255415912,205931156743,769994355746,2887687533958,10859294097589,40939724979676,154701255400490,585829636549849,2222842322625552
%N Number of permutations of [n] avoiding {2143, 4132, 1324}.
%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 172.
%p C := (1-sqrt(1-4*x))/2/x ;
%p ((2 -10*x +16*x^2 -8*x^3 +x^4)*C -1 +4*x -5*x^2 +x^3)/((1 -x)^2*(1 -3*x + x^2)) ;
%p taylor(%,x=0,40) ;
%p gfun[seriestolist](%) ;
%K nonn,easy
%O 0,3
%A _R. J. Mathar_, Nov 09 2017
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