Let n beads be arranged on a circle and indexed 0,1,…,n−1. Each bead is colored by an element of the finite field F7=Z/7Z. Two colorings (c0,…,cn−1)∈F7n are considered equivalent if one can be obtained from the other by a rotation or reflection of the necklace (that is, by the usual dihedral action Dn on indices).
A coloring is admissible if it satisfies all three linear constraints in F7:
i=0∑n−1cii=0∑n−1ici0≤i≤n−1i≡0 (mod 3)∑ci≡0≡0≡1(mod 7)(mod 7)(mod 7)
For this problem, take n=30. How many Dn-equivalence classes of admissible colorings are there for n=30? Report your answer modulo 1,000,003 as a positive integer.