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O.g.f.: -(1+x+2*x^2)/((3*x-1)*(x+1)*(x^2-x+1)) = -(3/2)/(3*x-1)+(1/3)*(x-2)/(x^2-x+1)+(1/ 6)/(x+1) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 28 2007
a(n) = 0.5*3^(n+1)+(1/6)*(-1)^n-(2/3)*cos(Pi*n/3). Or, a(n)=0.5*3^(n+1)+0.5*[ -1; -1; 1; 1; 1; -1]. - Richard Choulet (richardchoulet(AT)yahoo.fr), Jan 02 2008
a(n)=-(1/3)*{1/2-(1/2)*I*sqrt(3)}^n+(3/2)*3^n+(1/6)*(-1)^n-(1/3)*{1/2+(1/2)*I*sqrt(3)}^n, with n>=0 and I=sqrt(-1) - Paolo P. Lava (ppl(AT)spl.at), Jun 09 2008
a(n+1)-3a(n) = A132367(n+1). - Paul Curtz (bpcrtz(AT)free.fr), Dec 02 2007
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