Let Gn be the graph
of permutations with edges drawn between permutations differing by an
adjacent transposition. Using the Kazhdan-Lusztig representations of Sn
and combinatorial arguments, we show that integers frequently occur in the
spectrum of Gn. That 0 and −1 are among the integers which arise has
application to finite Radon transforms and to existence of perfect 1-codes on
Gn.