Proceedings of the London Mathematical Society Advance Access published online on April 25, 2008
Proceedings of the London Mathematical Society, doi:10.1112/plms/pdn006
© 2008 London Mathematical Society
Minimal vanishing sums of roots of unity with large coefficients
Received 26 April 2007. Revision received 27 July 2007.
A vanishing sum
, where
n is a primitive nth root of unity and the ais are non-negative integers is called minimal if the coefficient vector (a0, ..., an–1) does not properly dominate the coefficient vector of any other such non-zero sum. We show that for every c
there is a minimal vanishing sum of nth roots of unity with its greatest coefficient equal to c, where n is of the form 3pq for odd primes p, q. This solves an open problem posed by Lenstra Jr.
This research was supported by NSF VIGRE grant DMS-0135345.