Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0.
A128564
Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =1a(7) =5a(8) =5a(9) =1a(10) =1a(11) =9a(12) =22a(13) =15a(14) =1a(15) =1a(16) =29a(17) =90a(18) =90a(19) =29a(20) =1a(21) =1a(22) =49a(23) =359a(24) =573a(25) =359a(26) =98a(27) =1a(28) =1a(29) =174
External references
- oeis: A128564