Product of proper divisors is larger than for any smaller number.

Terms

a(0) =1a(1) =4a(2) =6a(3) =8a(4) =10a(5) =12a(6) =18a(7) =20a(8) =24a(9) =30a(10) =36a(11) =48a(12) =60a(13) =72a(14) =84a(15) =90a(16) =96a(17) =108a(18) =120a(19) =168a(20) =180a(21) =240a(22) =336a(23) =360a(24) =420a(25) =480a(26) =504a(27) =540a(28) =600a(29) =630