a(n) = floor( Gamma(n+1/3) ).

Terms

a(0) =2a(1) =0a(2) =1a(3) =2a(4) =9a(5) =40a(6) =214a(7) =1355a(8) =9940a(9) =82834a(10) =773118a(11) =7988887a(12) =90540729a(13) =1116669003a(14) =14888920041a(15) =213407853922