31177872domain: NAppears in sequencesNumber of solutions mod 3^n to the simultaneous equations 2*(Y^4 + T^4) + X^4 + Z^4 = 2*(X^2 + Z^2)*(Y^2 + T^2) (mod 3^n), U^2 + Y^2 = X^2 + Z^2 (mod 3^n), T = 0 (mod 3), X^2 = Y^2 = Z^2 = U^2 = 1 (mod 3).at n=4A307814