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, 1), (-1, 0), (1, 0)}.
A151261
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, 1), (-1, 0), (1, 0)}.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =5a(4) =17a(5) =34a(6) =121a(7) =265a(8) =969a(9) =2246a(10) =8351a(11) =20118a(12) =75676a(13) =187524a(14) =711369a(15) =1801161a(16) =6876749a(17) =17710990a(18) =67962103a(19) =177474154a(20) =683797608a(21) =1806245948a(22) =6982719679a(23) =18624035846a(24) =72200420096a(25) =194169343564a(26) =754537816956
External references
- oeis: A151261