a(n) is the number of 2n-bead necklaces with exactly n different colored beads.

A337827

a(n) is the number of 2n-bead necklaces with exactly n different colored beads.

Terms

    a(0) =1a(1) =4a(2) =91a(3) =5106a(4) =510312a(5) =79419180a(6) =17758541160

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