DIOPHANTINE EQUATIONS DUE TO SMARANDACHE 1) Conjecture: Let k > 0 be an integer. There is only a finite number of solutions in integers p, q, x, y, each greater than 1, to the equation p q x - y = k. For k = 1 this was conjectured by Cassels (1953) and proved by Tijdeman (1976). References: [1] Ibstedt, H., "Surphing on the Ocean of Numbers - A Few Smarandache Notions and Similar Topics", Erhus University Press, Vail, 1997, pp. 59-69. [2] Smarandache, F., "Only Problems, not Solutions!", Xiquan Publ. Hse., Phoenix, 1994, unsolved problem #20. 2) Conjecture: Let k >= 2 be a positive integer. The diophantine equation y = 2x x ... x +1 1 2 k has infinitely many solutions in distinct primes y, x , x , ..., x . 1 2 k References: [1] Ibstedt, H., "Surphing on the Ocean of Numbers - A Few Smarandache Notions and Similar Topics", Erhus University Press, Vail, 1997, pp. 59-69. [2] Smarandache, F., "Only Problems, not Solutions!", Xiquan Publ. Hse., Phoenix, fourth edition, 1994, unsolved problem #11.