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), (0, 1), (1, 0)}.
A151280
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), (0, 1), (1, 0)}.
Terms
- a(0) =1a(1) =2a(2) =5a(3) =15a(4) =47a(5) =150a(6) =495a(7) =1672a(8) =5698a(9) =19636a(10) =68470a(11) =240342a(12) =848258a(13) =3012899a(14) =10753669a(15) =38519879a(16) =138501666a(17) =499728140a(18) =1807946861a(19) =6557502077a(20) =23843549009a(21) =86880613032a(22) =317170036587
External references
- oeis: A151280