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), (-1, 0), (-1, 1), (0, 1), (1, 0)}.

A151421

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), (-1, 0), (-1, 1), (0, 1), (1, 0)}.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =9a(4) =28a(5) =98a(6) =346a(7) =1275a(8) =4783a(9) =18309a(10) =71087a(11) =279361a(12) =1109452a(13) =4443790a(14) =17935281a(15) =72859781a(16) =297693439a(17) =1222522463a(18) =5043272843a(19) =20889707738a(20) =86844446667a(21) =362237124633

External references