Expansion of x^3*exp(-x)/(3*(1-x)).

Terms

a(0) =2a(1) =0a(2) =20a(3) =80a(4) =630a(5) =4928a(6) =44520a(7) =444960a(8) =4894890a(9) =58738240a(10) =763597692a(11) =10690366960a(12) =160355505310