Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of 2 n steps taken from {(-1, -1), (-1, 0), (-1, 1), (1, 0)}.
A151341
Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of 2 n steps taken from {(-1, -1), (-1, 0), (-1, 1), (1, 0)}.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =20a(4) =126a(5) =882a(6) =6732a(7) =54483a(8) =461890a(9) =4059770a(10) =36749648a(11) =340841228a(12) =3226474132a(13) =31079221500a(14) =303907314960
External references
- oeis: A151341