Numbers k such that k and k+1 both have 6 divisors.

Terms

a(0) =44a(1) =75a(2) =98a(3) =116a(4) =147a(5) =171a(6) =242a(7) =243a(8) =244a(9) =332a(10) =387a(11) =507a(12) =548a(13) =603a(14) =604a(15) =724a(16) =844a(17) =908a(18) =931a(19) =963a(20) =1075a(21) =1083a(22) =1251a(23) =1324a(24) =1412a(25) =1467a(26) =1556a(27) =1587a(28) =1675a(29) =1772