A033296


Number of paths from (0,0) to (3n,0) that stay in first quadrant (but may touch horizontal axis), where each step is (2,1),(1,2) or (1,1) and start with (1,2).


1


%I
%S 1,6,42,326,2706,23526,211546,1951494,18366882,175674054,1702686090,
%T 16686795846,165079509042,1646340228006,16534463822010,
%U 167081444125702,1697551974416706,17330661859937670,177699201786231530
%N Number of paths from (0,0) to (3n,0) that stay in first quadrant (but may touch horizontal axis), where each step is (2,1),(1,2) or (1,1) and start with (1,2).
%F z A^3, where A is the g. f. of A027307. Also: difference of A027307 and A032349.
%Y Cf. A027307, A032349.
%K nonn
%O 1,2
%A _Emeric Deutsch_
