Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1), U=(1,2), or d=(1,-1) and have k hills of the form ud (a hill is either a ud or a Udd starting at the x-axis).
A108433
Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1), U=(1,2), or d=(1,-1) and have k hills of the form ud (a hill is either a ud or a Udd starting at the x-axis).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =7a(4) =2a(5) =1a(6) =47a(7) =15a(8) =3a(9) =1a(10) =361a(11) =108a(12) =24a(13) =4a(14) =1a(15) =2977a(16) =865a(17) =184a(18) =34a(19) =5a(20) =1a(21) =25775a(22) =7334a(23) =1533a(24) =276a(25) =45a(26) =6a(27) =1a(28) =231103a(29) =64767
External references
- oeis: A108433