412190domain: NAppears in sequencesa(n) = Sum_{k <= n/2 } k*binomial(n-2k, 3k).at n=25A137359Number 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), (0, -1), (0, 1), (1, -1), (1, 1)}.at n=10A151473