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(2cos(8*2/9 pi) - 1)(2 cos(4*2/9 pi) - 1)(2 cos(2*2/9 pi) - 1)(2 cos(2/9 pi) - 1)
(2cos(8*2/9 pi) - 1)(2 cos(4*2/9 pi) - 1)(2 cos(2*2/9 pi) - 1)(2 cos(2/9 pi) - 1)
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