Triangle read by rows: T(n,k) gives the number of ballot sequences of length n having exactly k descents, n>=0, 0<=k<=n.
A238121
Triangle read by rows: T(n,k) gives the number of ballot sequences of length n having exactly k descents, n>=0, 0<=k<=n.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =2a(4) =0a(5) =0a(6) =3a(7) =1a(8) =0a(9) =0a(10) =5a(11) =5a(12) =0a(13) =0a(14) =0a(15) =7a(16) =16a(17) =3a(18) =0a(19) =0a(20) =0a(21) =11a(22) =43a(23) =21a(24) =1a(25) =0a(26) =0a(27) =0a(28) =15a(29) =99
External references
- oeis: A238121