a(n) = floor( Gamma(n + 2/5)/Gamma(2/5) ).

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =4a(5) =20a(6) =108a(7) =694a(8) =5142a(9) =43193a(10) =406016a(11) =4222569a(12) =48137291a(13) =596902408a(14) =7998492273a(15) =115178288736