Number of subsets of {1,.., n} containing no twin prime pairs.

Terms

a(0) =2a(1) =4a(2) =8a(3) =16a(4) =24a(5) =48a(6) =80a(7) =160a(8) =320a(9) =640a(10) =1280a(11) =2560a(12) =3840a(13) =7680a(14) =15360a(15) =30720a(16) =61440a(17) =122880a(18) =184320a(19) =368640a(20) =737280a(21) =1474560a(22) =2949120a(23) =5898240a(24) =11796480a(25) =23592960a(26) =47185920a(27) =94371840a(28) =188743680a(29) =377487360