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

A151443

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

Terms

    a(0) =1a(1) =1a(2) =3a(3) =6a(4) =23a(5) =57a(6) =241a(7) =667a(8) =2966a(9) =8784a(10) =40295a(11) =124964a(12) =585435a(13) =1877481a(14) =8929621a(15) =29378968a(16) =141326855a(17) =474458386a(18) =2302594186a(19) =7857845926a(20) =38404279674a(21) =132849003739a(22) =653019772711

External references