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, 0)}.

A151376

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, 0)}.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =6a(5) =10a(6) =31a(7) =72a(8) =143a(9) =448a(10) =1113a(11) =2420a(12) =7607a(13) =19644a(14) =45166a(15) =142062a(16) =376222a(17) =898670a(18) =2825125a(19) =7615948a(20) =18705781a(21) =58744868a(22) =160472382a(23) =402623434a(24) =1262880382a(25) =3485281642a(26) =8893103765a(27) =27858544576a(28) =77513822785a(29) =200511910392

External references