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), (0, 1), (1, -1), (1, 0)}.
A151397
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), (0, 1), (1, -1), (1, 0)}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =3a(4) =8a(5) =15a(6) =40a(7) =130a(8) =326a(9) =854a(10) =2812a(11) =8328a(12) =22849a(13) =72679a(14) =233635a(15) =686180a(16) =2131348a(17) =7032223a(18) =21948203a(19) =68247127a(20) =224907904a(21) =731136007a(22) =2315461477a(23) =7582271275a(24) =25158427804a(25) =81559484413a(26) =266864101260a(27) =891674092876
External references
- oeis: A151397