a(n) = floor( Gamma(n + 5/6)/Gamma(5/6) ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =16a(5) =80a(6) =467a(7) =3196a(8) =25042a(9) =221208a(10) =2175216a(11) =23564850a(12) =278850730a(13) =3578584368a(14) =49503750432a(15) =734305631412