Middle of three consecutive semiprimes with common prime factor = 3.

Terms

a(0) =3909a(1) =87627a(2) =132609a(3) =163491a(4) =167451a(5) =170679a(6) =209289a(7) =224151a(8) =270591a(9) =309273a(10) =318651a(11) =327423a(12) =340077a(13) =395121a(14) =444459a(15) =481863a(16) =497121a(17) =522231a(18) =536451a(19) =584589a(20) =624837a(21) =633189a(22) =680451a(23) =752901a(24) =765579a(25) =767757a(26) =830469a(27) =848739a(28) =878133a(29) =915063