Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (0, -1), (1, 1)}.
A151270
Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (0, -1), (1, 1)}.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =9a(4) =30a(5) =90a(6) =286a(7) =941a(8) =3072a(9) =10308a(10) =34814a(11) =118138a(12) =406368a(13) =1399630a(14) =4858636a(15) =16948153a(16) =59302432a(17) =208587930a(18) =735602234a(19) =2602943312a(20) =9239044912a(21) =32867768218a(22) =117244508016a(23) =419105764722
External references
- oeis: A151270