Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #7 Sep 09 2017 11:43:12
%S 1,4,96,384,34560,4147200,23224320,6220800,99532800,1605264998400,
%T 10319560704000,52973744947200,2517312359890944000,137731736862720000,
%U 104125193068216320000,1039086126666344300544000000
%N Integers of the form phi(n!)/phi(n)!.
%t Select[Table[EulerPhi[n!]/EulerPhi[n]!,{n,50}],IntegerQ] //DeleteDuplicates (* _Harvey P. Dale_, Sep 09 2017 *)
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, Mar 17 2002