Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 0), (0, -1), (1, 1)}.
A151265
Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 0), (0, -1), (1, 1)}.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =7a(4) =17a(5) =47a(6) =125a(7) =333a(8) =939a(9) =2597a(10) =7183a(11) =20505a(12) =57859a(13) =163201a(14) =469795a(15) =1341775a(16) =3830529a(17) =11092823a(18) =31940165a(19) =91927379a(20) =267406401a(21) =774447755a(22) =2242022721a(23) =6544458687a(24) =19036737381a(25) =55354815639a(26) =162028272261a(27) =472921269031
External references
- oeis: A151265