J. Sichuan Univ., Nat. Sci. Ed. 26, Spec. Issue, 196-200 (1989).
. The author studies the square classes of the second order linear recurrence sequences
, that is the question when
a square with distinct m,n. It is proved that
can not be a square with
. The same is shown for the sequence
if a is even. If a is odd, then there exist an effectively computable constant C such that if
is square with