For

, let

denote the number of representations of

in the form

,
where

. A set

is called a unique
difference basis of

if

for all

in

. In this paper, we prove that there exists a unique
difference basis of

whose growth is logarithmic. These
results show that the analogue of the Erdos-Turán conjecture
fails to hold in

.
Received October 12 2010;
revised version received January 26 2011.
Published in Journal of Integer Sequences, February 9 2011.