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), (0, 1), (1, 1)}.
A151405
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), (0, 1), (1, 1)}.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =8a(4) =23a(5) =75a(6) =238a(7) =800a(8) =2734a(9) =9417a(10) =33207a(11) =117661a(12) =421563a(13) =1524047a(14) =5537482a(15) =20269868a(16) =74545781a(17) =275422975a(18) =1022213776a(19) =3806863892a(20) =14227928563a(21) =53338307668a(22) =200505927183a(23) =755722398596
External references
- oeis: A151405