a(n) = Product_{d|n, d<n} A019565(d)^[0 == d mod 3].

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =6a(6) =1a(7) =1a(8) =6a(9) =1a(10) =1a(11) =90a(12) =1a(13) =1a(14) =6a(15) =1a(16) =1a(17) =1260a(18) =1a(19) =1a(20) =6a(21) =1a(22) =1a(23) =3150a(24) =1a(25) =1a(26) =84a(27) =1a(28) =1a(29) =18900