Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 4 adjacent element pairs in decreasing order.
A151585
Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 4 adjacent element pairs in decreasing order.
Terms
- a(0) =0a(1) =3a(2) =976a(3) =44275a(4) =1046556a(5) =18098871a(6) =262962368a(7) =3438697635a(8) =42050013500
External references
- oeis: A151585