E.g.f. (1-x^3)/(1-x^2-x^3).

Terms

a(0) =1a(1) =0a(2) =2a(3) =0a(4) =24a(5) =120a(6) =720a(7) =10080a(8) =80640a(9) =1088640a(10) =14515200a(11) =199584000a(12) =3353011200a(13) =56043187200