Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 1), (0, 1), (1, -1)}.
A151390
Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 1), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =13a(6) =33a(7) =88a(8) =256a(9) =706a(10) =2150a(11) =6274a(12) =19646a(13) =59393a(14) =190957a(15) =592500a(16) =1940660a(17) =6150996a(18) =20448656a(19) =65920110a(20) =221846298a(21) =725218554a(22) =2465440766a(23) =8154637122a(24) =27960144414a(25) =93407091930a(26) =322618540398
External references
- oeis: A151390