Triangle read by rows: T(n,k) is the number of even permutations of {1,2,...,n} having k descents (n >= 1, k >= 0).
A145882
Triangle read by rows: T(n,k) is the number of even permutations of {1,2,...,n} having k descents (n >= 1, k >= 0).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =1a(5) =5a(6) =5a(7) =1a(8) =1a(9) =14a(10) =30a(11) =14a(12) =1a(13) =1a(14) =29a(15) =147a(16) =155a(17) =28a(18) =1a(19) =64a(20) =586a(21) =1208a(22) =605a(23) =56a(24) =1a(25) =127a(26) =2133a(27) =7819a(28) =7819a(29) =2133
External references
- oeis: A145882