Number of inverse pairs of elements in symmetric group S_n, or pairs of total orders on n nodes (average of A000085 and A000142).
A007868
Number of inverse pairs of elements in symmetric group S_n, or pairs of total orders on n nodes (average of A000085 and A000142).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =5a(4) =17a(5) =73a(6) =398a(7) =2636a(8) =20542a(9) =182750a(10) =1819148a(11) =19976248a(12) =239570876a(13) =3113794652a(14) =43590340840a(15) =653842358768
External references
- oeis: A007868