Number of square lattice walks of length 2n starting and ending at (0,0) and avoiding the West quadrant {(i,j): i < -|j|}.

A260154

Number of square lattice walks of length 2n starting and ending at (0,0) and avoiding the West quadrant {(i,j): i < -|j|}.

Terms

    a(0) =1a(1) =3a(2) =22a(3) =209a(4) =2256a(5) =26296a(6) =322696a(7) =4109131a(8) =53802868a(9) =719967204a(10) =9804170810a(11) =135438150718

External references