a(n) = Product_{d|n, d<n} A019565(phi(d)), where phi is the Euler totient function A000010.

Terms

a(0) =1a(1) =2a(2) =2a(3) =4a(4) =2a(5) =12a(6) =2a(7) =12a(8) =6a(9) =20a(10) =2a(11) =108a(12) =2a(13) =60a(14) =30a(15) =60a(16) =2a(17) =540a(18) =2a(19) =300a(20) =90a(21) =84a(22) =2a(23) =2700a(24) =10a(25) =140a(26) =90a(27) =2700a(28) =2a(29) =6300