Number of circular permutations of the multiset {1,1,2,2,...,n,n} (up to rotations).
A137729
Number of circular permutations of the multiset {1,1,2,2,...,n,n} (up to rotations).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =16a(4) =318a(5) =11352a(6) =623760a(7) =48648960a(8) =5108105520a(9) =694702028160
External references
- oeis: A137729