Counting integers representable as images of polynomials modulo n

Given a polynomial f(x1,x2,…,xt) in t variables with integer coefficients and a positive integer n, let α(n) be the number of integers 0 ≤ a < n such that the polynomialcongruencef(x1,x2,…,xt) ≡ a(modn)issolvable. Wedescribeamethod that allows us to determine the function α associated with polyno...