  We prove that for a positive integer a the integer sequence P(n) satisfying
for all n, -infty<n<infty, the recurrence P(n)=a+P(n-phi(a)), phi(a) the Euler
function, generates in increasing order all integers P(n) coprime to a.The
finite Fourier expansion of P(n) is given in terms of a, n, and the phi(a)-th
roots of unity. Properties of the sequence are derived.
