Triangular array read by rows. T(n,k) is the number of ways to form an ordered pair of n-permutations and then choose a size k subset of its common descent set, n >= 0, 0 <= k <= max{0,n-1}.
A362589
Triangular array read by rows. T(n,k) is the number of ways to form an ordered pair of n-permutations and then choose a size k subset of its common descent set, n >= 0, 0 <= k <= max{0,n-1}.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =1a(4) =36a(5) =18a(6) =1a(7) =576a(8) =432a(9) =68a(10) =1a(11) =14400a(12) =14400a(13) =3900a(14) =250a(15) =1a(16) =518400a(17) =648000a(18) =252000a(19) =32400a(20) =922a(21) =1a(22) =25401600a(23) =38102400a(24) =19404000a(25) =3880800a(26) =262542a(27) =3430a(28) =1a(29) =1625702400
External references
- oeis: A362589