a(n) = Product_{(s - 2)|n, s prime} s if n > 0, a(0) = 1.

Terms

a(0) =1a(1) =3a(2) =3a(3) =15a(4) =3a(5) =21a(6) =15a(7) =3a(8) =3a(9) =165a(10) =21a(11) =39a(12) =15a(13) =3a(14) =3a(15) =1785a(16) =3a(17) =57a(18) =165a(19) =3a(20) =21a(21) =345a(22) =39a(23) =3a(24) =15a(25) =21a(26) =3a(27) =4785a(28) =3a(29) =93