573224305873domain: NAppears in sequencesa(n) = 6*a(n-1) - a(n-2), n >= 2, a(0)=1, a(1)=2.at n=16A038725Solutions (value of r) of the Diophantine equation 2*x^2 + 3*x + 2 = r^2.at n=15A055979