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), (1, 0)}.
A151408
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), (1, 0)}.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =34a(6) =97a(7) =287a(8) =887a(9) =2761a(10) =8833a(11) =28635a(12) =93897a(13) =312257a(14) =1046368a(15) =3539825a(16) =12066283a(17) =41387197a(18) =142887038a(19) =495828190a(20) =1729130445a(21) =6057385620a(22) =21303526484a(23) =75209346309a(24) =266413953357a(25) =946691896721
External references
- oeis: A151408