Number of returns to the x-axis in all 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).
A108436
Number of returns to the x-axis in all 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).
Terms
- a(0) =2a(1) =14a(2) =106a(3) =862a(4) =7378a(5) =65550a(6) =599002a(7) =5594942a(8) =53181730a(9) =512784142a(10) =5003410762a(11) =49312114334a(12) =490192537586
External references
- oeis: A108436