Triangle read by rows: T(n,k) is the number of Schroeder paths of length 2n and having k weak ascents (1<=k<=n). A Schroeder path of length 2n is a lattice path from (0,0) to (2n,0) consisting of U=(1,1), D=(1,-1) and H=(2,0) steps and never going below the x-axis. A weak ascent in a Schroeder path is a maximal sequence of consecutive U and H steps.
A114655
Triangle read by rows: T(n,k) is the number of Schroeder paths of length 2n and having k weak ascents (1<=k<=n). A Schroeder path of length 2n is a lattice path from (0,0) to (2n,0) consisting of U=(1,1), D=(1,-1) and H=(2,0) steps and never going below the x-axis. A weak ascent in a Schroeder path is a maximal sequence of consecutive U and H steps.
Terms
- a(0) =2a(1) =4a(2) =2a(3) =8a(4) =12a(5) =2a(6) =16a(7) =48a(8) =24a(9) =2a(10) =32a(11) =160a(12) =160a(13) =40a(14) =2a(15) =64a(16) =480a(17) =800a(18) =400a(19) =60a(20) =2a(21) =128a(22) =1344a(23) =3360a(24) =2800a(25) =840a(26) =84a(27) =2a(28) =256a(29) =3584
External references
- oeis: A114655