a(0) = 0, a(n) = 4*n! for n > 0.

Terms

a(0) =0a(1) =4a(2) =8a(3) =24a(4) =96a(5) =480a(6) =2880a(7) =20160a(8) =161280a(9) =1451520a(10) =14515200a(11) =159667200a(12) =1916006400a(13) =24908083200a(14) =348713164800