A polynomial P(x) of degree 3n has the value 2 at x= 0, 3, 6,..., 3n, and:
the value 1 at x= 1, 4, 7, ... , 3n-2, and:
the value 0 at x= 2, 5, 8, ... , 3n-1.

Given that P(3n+1) = 730, find n.