a(n) is the number of lattice paths from (0,0) to (3n,2n) using only the steps (1,0) and (0,1) and which do not touch any other points of the form (3k,2k).

A337351

a(n) is the number of lattice paths from (0,0) to (3n,2n) using only the steps (1,0) and (0,1) and which do not touch any other points of the form (3k,2k).

Terms

    a(0) =1a(1) =10a(2) =110a(3) =1805a(4) =34770a(5) =731760a(6) =16295600a(7) =377438250a(8) =8999246900a(9) =219399101415

External references