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 no peaks of the form ud.
A108447
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 no peaks of the form ud.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =20a(4) =113a(5) =688a(6) =4404a(7) =29219a(8) =199140a(9) =1385904a(10) =9807820a(11) =70364704a(12) =510609620a(13) =3741212535a(14) =27639233548a(15) =205660399220
External references
- oeis: A108447