a(n) = floor( Gamma(n+2/3) ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =14a(5) =68a(6) =389a(7) =2593a(8) =19884a(9) =172328a(10) =1665837a(11) =17768938a(12) =207304278a(13) =2625854188a(14) =35886673906a(15) =526337883959