a(n) = phi(n!)/phi(n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =8a(5) =96a(6) =192a(7) =2304a(8) =13824a(9) =207360a(10) =829440a(11) =24883200a(12) =99532800a(13) =2786918400a(14) =31352832000a(15) =501645312000