Number of 2n-bead necklaces labeled with numbers 1..7 not allowing reversal, with neighbors differing by exactly 1.

A208726

Number of 2n-bead necklaces labeled with numbers 1..7 not allowing reversal, with neighbors differing by exactly 1.

Terms

    a(0) =6a(1) =11a(2) =20a(3) =45a(4) =104a(5) =290a(6) =796a(7) =2366a(8) =7076a(9) =21684a(10) =66996a(11) =209594a(12) =659560a(13) =2090590a(14) =6659120a(15) =21312716a(16) =68476512a(17) =220798322a(18) =714144612a(19) =2316303916a(20) =7531662344a(21) =24545750474a(22) =80160395804a(23) =262280793024a(24) =859662037240

External references