Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 6 adjacent element pairs in decreasing order.
A151587
Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 6 adjacent element pairs in decreasing order.
Terms
- a(0) =0a(1) =4a(2) =11565a(3) =2580588a(4) =229630758a(5) =12719963448a(6) =531411968223
External references
- oeis: A151587