The Quarterly Journal of Mathematics Advance Access published online on October 30, 2007
The Quarterly Journal of Mathematics, doi:10.1093/qmath/ham044
THE AVERAGE VALUE OF DIVISOR SUMS IN ARITHMETIC PROGRESSIONS

Department of Mathematics, University of Toronto, 40 St George Street, Toronto, Ontario, Canada M5S 2E4
Corresponding author. E-mail: vblomer{at}math.toronto.edu
Received 9 April 2007;
revised 4 June 2007
| Abstract |
|---|
Let
(n) denote the Fourier coefficients of cusp forms or the number of divisors of n. Estimates of the type
are shown, uniformly in q
X. The methods can be extended to other arithmetic functions, for example, the number of representations of n as a sum of two squares or k-free numbers. As an application, sums of the type
n
X
(n)
(n) for any q-periodic function
can be estimated non-trivially.