a(n) = Product_{k=1..n-1} phi(gcd(n,k)).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =1a(7) =2a(8) =4a(9) =4a(10) =1a(11) =32a(12) =1a(13) =6a(14) =256a(15) =16a(16) =1a(17) =96a(18) =1a(19) =1024a(20) =2304a(21) =10a(22) =1a(23) =16384a(24) =256a(25) =12a(26) =2304a(27) =13824a(28) =1a(29) =524288