“tau of n” was composed for the new music ensemble, Thamyris. It was first performed by that group in 1992 in a concert at Spivey Hall. The mathematical expression “tau of n” is a function encountered in number theory. Also called the “divisor function,” when applied to a positive integer, “tau of n” produces a result which is the number of positive divisors of that integer. For example: the numbers 1 and 3 are all of the possible positive divisors of 3, so r(3)=2. Likewise, 1,2,5 and 10 are all of the positive divisors of 10, so r(10)=4.