Numbers such that the two numbers before and the two numbers after are squarefree semiprimes.

Terms

a(0) =144a(1) =204a(2) =216a(3) =300a(4) =696a(5) =1140a(6) =1764a(7) =2604a(8) =3240a(9) =3900a(10) =4536a(11) =4764a(12) =5316a(13) =5460a(14) =6000a(15) =6504a(16) =7116a(17) =7836a(18) =7860a(19) =8004a(20) =8484a(21) =9300a(22) =9864a(23) =9936a(24) =10020a(25) =11760a(26) =12180a(27) =13140a(28) =13656a(29) =14256