Number of permutations of 3 indistinguishable copies of 1..n arranged in a circle with exactly 2 adjacent element pairs in decreasing order.

A151590

Number of permutations of 3 indistinguishable copies of 1..n arranged in a circle with exactly 2 adjacent element pairs in decreasing order.

Terms

    a(0) =0a(1) =12a(2) =207a(3) =1392a(4) =7455a(5) =36540a(6) =171591a(7) =785856a(8) =3538215a(9) =15727740a(10) =69204927a(11) =301988592a(12) =1308621327a(13) =5637142812a(14) =24159189015a(15) =103079212800a(16) =438086661591

External references