Access binary representation of f Galois field by having power of X?

i use gf(2^4) using x^4+x+1

I want to access to binary value for specific equation by konwing power of X

Ex: if the polynmial is : X^3+1 the binary representation of it when using gf(2^4) is : 1001 ....How we do it?

y = gf(0:15,4);