Numbers having divisors d, e with d < e < 2*d.

Terms

a(0) =6a(1) =12a(2) =15a(3) =18a(4) =20a(5) =24a(6) =28a(7) =30a(8) =35a(9) =36a(10) =40a(11) =42a(12) =45a(13) =48a(14) =54a(15) =56a(16) =60a(17) =63a(18) =66a(19) =70a(20) =72a(21) =75a(22) =77a(23) =78a(24) =80a(25) =84a(26) =88a(27) =90a(28) =91a(29) =96