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304                        HlSTOEY OF THE THEORY OF  NUMBERS.                   [CHAP. X
sth powers of the divisors of n whose complementary divisors are even, the excess f '8(n) of the sum of the sth powers of the divisors whose complementary divisors -are odd over that when they are even, and the similar 'functions74 A'a, f  <rg. The seven functions can be expressed in terms of any two:
where the arguments are all n. Since D'8(2k) =<rs(k), we may express all the functions in terms of <r8(n) and <r,(n/2), provided the latter be defined to be zero when n is odd. Employ the abbreviation S/F=SjF/ for
This sum is evaluated when/ and F are any two of the above seven functions with s = 1 (the subscript 1 is dropped).    If
By using the first formula in each of two earlier papers,74'75 we get
' = 5D3'(n) -24Sol)' = 2<r3(n) + (1 -3n)(r(n) + (1 -6n)Z)'(n) +8>3'(n).
Hence all 21 functions can now be expressed at once linearly in terms of or3, D3', <r and D'. The resulting expressions are tabulated; they give the coefficients in the products of any two of the series Z*/(n)af, where /is any one of our seven functions without subscript.
Glaisher88 gave the values of So"3<rt- for i = 3, 5, 9 and Sor5cr7, where the notation is that of the preceding paper..   Also, if p = n r,
12 2 r/xr(r)er(p) =nV3(n) -nV(n),          S r/(r)F(p) =^2/F.
r-l                                                   r=l                  2
L. Gegenbauer89 gave purely arithmetical proofs of generalizations of theorems obtained by Hermite70 by use of elliptic function expansions.   Let
&(r)= S jfc,           er= S
;-l                        x=l
Then (p. 1059),
The left member is known to equal the sum of the kth powers of all the divisors of 1, 2, . . ., n. The first sum on the right is the sum of the Mi powers of the divisors ^ \/n of 1, . . . , n. Hence if Ak(x) is the excess of the
88Messenger Math., 15, 1885-6, p. 36.
"Sitzungsberichte Ak. Wien (Math.), 92, II, 1886, 1055-78.