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%I A025256 #9 Aug 31 2020 18:57:04
%S A025256 1,1,3,3,6,18,42,105,291,792,2181,6177,17628,50679,147255,430917,
%T A025256 1268292,3754926,11172828,33389040,100181994,301682709,911436117,
%U A025256 2761852011,8392005462,25563691341,78053071611,238830914937,732247187460,2249217635238
%N A025256 a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-3)*a(3) for n >= 4.
%F A025256 G.f.: (1+x+x^2-sqrt(1-2*x-x^2-10*x^3+x^4))/2. - _Vladeta Jovovic_, May 07 2003
%F A025256 Conjecture: n*a(n) +(-2*n+3)*a(n-1) +(-n+3)*a(n-2) +5*(-2*n+9)*a(n-3) +(n-6)*a(n-4)=0. - _R. J. Mathar_, Feb 25 2015
%t A025256 CoefficientList[Series[(1+x+x^2-Sqrt[(1-2x-x^2-10x^3+x^4)])/2,{x,0,40}],x] (* _Harvey P. Dale_, Aug 31 2020 *)
%K A025256 nonn
%O A025256 1,3
%A A025256 _Clark Kimberling_

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