I believe you mean "describable by a polynomial formula", in which case the answer is "yes".
Given n terms s\sb 0, \cdots, s\sb {n-1} http://latex.mathoverflow.net/png?s%5F0%2C%20%5Ccdots%2C%20s%5F%7Bn%2D1%7D, start with a polynomial of degree n:
Create a system of n equations such that for each polynomial where x = 0, .. , n-1 the polynomial is set equal to s\sb 0, \cdots, s\sb {n-1} http://latex.mathoverflow.net/png?s%5F0%2C%20%5Ccdots%2C%20s%5F%7Bn%2D1%7D.
Solve the system of equations for all terms a\sb 1, \cdots, a\sb n http://latex.mathoverflow.net/png?a%5F1%2C%20%5Ccdots%2C%20a%5Fn and voila, a formula.
Now repeat the same thing for a polynomial of one higher degree, dropping the a\sb {n-1}x http://latex.mathoverflow.net/png?a%5F%7Bn%2D1%7Dx term so there are still n terms in total.
Voila, a second formula.