137379191138domain: NAppears in sequencesa(0) = 3, a(1) = 8, a(n+2) = 4*a(n+1) - a(n) - 2.at n=19A102206a(n) = ((sqrt(3)+1)^n+(sqrt(3)-1)^n)^2/2^(n+1).at n=20A121401