( 28 ) 
and from this formula for n= 1- 
Ayn 
A) == GE 4 TONE B 
whereas for larger values of n we-can write in general 
92n 
Z (2n) = 2 w—2"C (2n) aa Ten 
Wen) (0) . 
Now considering the expansion 
y2n—2 
u (An—2)!" 
where the leading coefficient A, is zero and the other À’s stand for 
certain known polynomials in the invariants gy and gs, we deduce 
from it 
(u) = E u2n-2 be PER Ree 2 Bs 
cat eae as PM CP niet. ae 
and 
An - al 5 
wen?) (0) = ae Cor I (2) L(2n), 
so that we find 
Erten ds 
(27)! 
provided x be greater than 1. 
In order to obtain an expression of the numbers Z, of Hurwitz 
we take 
In this special case we have 
hon +1 is doo wae Ie 
where Z, is a rational and positive number, obeying the relation 
(4n)! 
(2a) 
this relation obviously being the analogue of the well known 
formula for the Bernoullian numbers 
(2n)! 
- ie m)en 
Zang, lis 
ie 
(Lf e152) . athe 
