%I #9 Sep 27 2019 12:39:49
%S 1,2,6,8,120,12,5040,384,324,80,39916800,144,6227020800,672,90,
%T 10321920,355687428096000,2592,121645100408832000,1600,756,84480,
%U 25852016738884976640000,62208,9000000,1198080,14285134080,18816
%N a(n) = product of the positive integers k, k<= n, such that the positive integers <= k and coprime to k are also coprime to n.
%e The positive integers k, k <= 6, where the positive integers <= k and coprime to k are also coprime to 6, are 1,2,6. So a(6) = 1*2*6 = 12.
%t f[n_] := Select[Range[n], GCD[ #, n] == 1 &];g[n_] := Select[Range[n], Times @@ GCD[f[ # ], n] == 1 &];Times @@@ Table[g[n], {n, 30}] (* Ray Chandler, Dec 24 2006 *)
%Y Cf. A126260, A124611.
%K nonn
%O 1,2
%A _Leroy Quet_, Dec 24 2006
%E Extended by _Ray Chandler_, Dec 24 2006