We consider the Yangian invariant eigenstates, ''motifs'', of the Hald
ane-Shastry type spin systems. We relate the Rogers-Szego polynomial t
o the representation of motifs through the partition function of the H
aldane-Shastry type spin model. We further discuss the relationship be
tween the generalized Rogers-Szego polynomial and the Yangian Y(su(n))
.