ME. W. SPOTTISWOODE ON THE CALCULUS OF SYMBOLS. 
119 
The expressions (10.) for the formation of the Os admit of further development thus: 
Oo=cPi,- 
-MM- MM 
+ <Pn-2 5 
or writing, by analogy to the Os, 
the expression for O 2 becomes 
And so likewise writing 
it will be found that 
M(M-l)(M-2) , /Oo\"' (M-l)(M-2) , /% 
*^3 >'-3 
£n 
M-3 
\I'\r 
