If 1, ω, ω² are the cube roots of unity and n ∈ N, then D = \(\left| {\begin{array}{*{20}{c}} 1&{{\omega ^n}}&{{\omega ^{2n}}}\\ {{\omega ^{2n}}}&{{\omega ^n}}&1\\ {{\omega ^{2n}}}&1&{{\omega ^n}} \end{array}} \right|\) is equal to