We prove that if
(x,y,n,q)≠(18,7,3,3) is a solution of the Diophantine equation (xn− 1)∕(x− 1) = yq
with q prime, then there exists a prime number p such that p divides x
and q divides p − 1. This allows us to solve completely this Diophantine
equation for infinitely many values of x. The proofs require several different
methods in diophantine approximation together with some heavy computer
calculations.