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, 0), (-1, 1), (0, 1), (1, -1)}.
A151335
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, 0), (-1, 1), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =0a(2) =0a(3) =1a(4) =0a(5) =1a(6) =5a(7) =1a(8) =18a(9) =43a(10) =47a(11) =313a(12) =570a(13) =1480a(14) =5847a(15) =11715a(16) =41194a(17) =124918a(18) =317707a(19) =1120909a(20) =3159179a(21) =9581991a(22) =31624946a(23) =92407981a(24) =300936377a(25) =954921610a(26) =2965630143a(27) =9769316877a(28) =30986916602a(29) =100406899586
External references
- oeis: A151335