Numbers k such that k and k+2 both have exactly 6 divisors.

Terms

a(0) =18a(1) =50a(2) =242a(3) =243a(4) =423a(5) =475a(6) =603a(7) =637a(8) =722a(9) =845a(10) =925a(11) =1682a(12) =1773a(13) =2007a(14) =2523a(15) =2525a(16) =2527a(17) =3123a(18) =3175a(19) =3177a(20) =4203a(21) =4475a(22) =4525a(23) =4923a(24) =5823a(25) =6725a(26) =6811a(27) =6962a(28) =7299a(29) =7442