/ 2\ / 4\ / 8\ (x + a)*\x + a /*\x + a /*\x + a /
(a + x)*(x + a^2)*(x + a^4)*(x + a^8)
15 4 3 7 11 13 14 2 3 3 2 4 3 5 2 6 2 8 3 9 2 10 2 12 2 a + x + a*x + x*a + x*a + x*a + x*a + a *x + a *x + a *x + a *x + a *x + a *x + a *x + a *x + a *x