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, 0), (0, 1), (1, -1)}.
A151378
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, 0), (0, 1), (1, -1)}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =7a(6) =16a(7) =37a(8) =78a(9) =191a(10) =472a(11) =1091a(12) =2784a(13) =7152a(14) =17460a(15) =45788a(16) =120682a(17) =305441a(18) =816698a(19) =2192203a(20) =5691926a(21) =15441378a(22) =42019320a(23) =111194238a(24) =305061352a(25) =839027467a(26) =2253118896a(27) =6237085427a(28) =17301189778a(29) =47005703891
External references
- oeis: A151378