A294696 - OEIS

%I #8 Mar 21 2021 21:40:34

%S 1,1,2,6,21,73,243,785,2511,8073,26312,87257,294603,1011602,3526519,

%T 12456315,44495535,160468964,583421709,2135814678,7865015071,

%U 29109558620,108213772256,403835324635,1512193773211,5679789173645,21391713994138,80767323230065,305638129059811,1158989815141334,4403331448837253

%N Number of permutations of [n] avoiding {1423, 2341, 3124}.

%H D. Callan, T. Mansour, <a href="http://arxiv.org/abs/1708.00832">Enumeration of small Wilf Classes avoiding 1342 and two other 4-letter patterns</a>, arXiv:1708.00832 (2017). Table 1 No 103.

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

%p p := 1-9*x+35*x^2-77*x^3+107*x^4-97*x^5+55*x^6-17*x^7+x^8 ;

%p q := (1-x)^5*(1-4*x+5*x^2-3*x^3) ;

%p taylor(p/q*C,x=0,40) ;

%p gfun[seriestolist](%) ;

%K nonn,easy

%O 0,3

%A _R. J. Mathar_, Nov 07 2017