a(n) = 2*a(n-1)^2/3-3 with a(0)=6.A213680a(n) = 2*a(n-1)^2/3-3 with a(0)=6.Terms a(0) =6a(1) =21a(2) =291a(3) =56451a(4) =2124476931External referencesoeis: A213680