Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 1), (1, -1), (1, 0)}.
A151371
Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 1), (1, -1), (1, 0)}.
Terms
- a(0) =1a(1) =0a(2) =2a(3) =4a(4) =16a(5) =64a(6) =266a(7) =1210a(8) =5630a(9) =27338a(10) =136182a(11) =695270a(12) =3622134a(13) =19202912a(14) =103375978a(15) =564014502a(16) =3114100008a(17) =17377324802a(18) =97897946434a(19) =556290574936
External references
- oeis: A151371