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), (1, 1)}.
A151272
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), (1, 1)}.
Terms
- a(0) =1a(1) =1a(2) =4a(3) =11a(4) =34a(5) =112a(6) =376a(7) =1257a(8) =4330a(9) =15068a(10) =52570a(11) =185086a(12) =657128a(13) =2339972a(14) =8366910a(15) =30070119a(16) =108400594a(17) =391749772a(18) =1420203840a(19) =5161860950a(20) =18797194292a(21) =68593029228a(22) =250803101058a(23) =918497353314
External references
- oeis: A151272