228167522domain: NAppears in sequencesX-values of solutions to the equation X*(X + 1) - 6*Y^2 = 0.at n=9A132596a(n) = -cos((2*n-1)*arcsin(sqrt(3)))^2 = -1 + cosh((2*n-1)*arcsinh(sqrt(2)))^2.at n=4A146312