a(n) = floor( Gamma(n+3/4) ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =16a(5) =78a(6) =453a(7) =3057a(8) =23698a(9) =207358a(10) =2021746a(11) =21733773a(12) =255371835a(13) =3255990905a(14) =44769874946a(15) =660355655453