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Square classes of (a n -1)/(a-1) and a n +1. (English) Zbl 0709.11014
J. Sichuan Univ., Nat. Sci. Ed. 26, Spec. Issue, 196-200 (1989).
Let a>1, n1 be integers, U n =(a n -1)/(a-1), V n =a n +1. The author studies the square classes of the second order linear recurrence sequences U n ,V n , that is the question when U m U n or V m V n is a square with distinct m,n. It is proved that U m U n can not be a square with mn. The same is shown for the sequence V n if a is even. If a is odd, then there exist an effectively computable constant C such that if V m V n is square with mn then a,m,n<C.
Reviewer: I.Gaál

MSC:
11B37Recurrences
11D41Higher degree diophantine equations