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%I #9 Jun 14 2016 12:53:33
%S 1,1,2,6,23,103,488,2320,10867,49971,225861,1005821,4423807,19255967,
%T 83093364,355956164,1515437339,6417727259,27054820649,113602953089,
%U 475370846639,1983142721039,8250982614809,34246497698633,141838788939623,586322071478503,2419474311617803,9968270142800955,41010408788528703,168499207575017087
%N Expansion of the conjectured generating function for the number of "almost avoiding" permutations in the set Av(321)^{+1}.
%D R. Brignall et al., Almost avoiding permutations, Discrete Math., 309 (2009),6626-6631.
%F G.f.: (1-8*x+13*x^2+24*x^3-48*x^4-(1-6*x+x^2+34*x^3-26*x^4-4*x^5)*sqrt(1-4*x))/
%F (2*x^2*(1 -x)*(1- 4*x)^2)
%F Conjecture: -(n+2)*(404489*n-1866368)*a(n) +(3147815*n^2-8680082*n-14098754)*a(n-1) +2*(-2336439*n^2+652022*n+14514849)*a(n-2) +8*(-1044770*n^2+10585023*n-20370553)*a(n-3) +8*(642982*n-2004177)*(2*n-9)*a(n-4)=0. - _R. J. Mathar_, Jun 14 2016
%Y Cf. A174195.
%K nonn
%O 0,3
%A _N. J. A. Sloane_, Nov 26 2010
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