Number of subsets of {1...n} containing no prime indices of the elements.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =8a(5) =13a(6) =19a(7) =30a(8) =54a(9) =96a(10) =156a(11) =248a(12) =440a(13) =688a(14) =1120a(15) =1864a(16) =3664a(17) =5856a(18) =11232a(19) =16896a(20) =31296a(21) =53952a(22) =91008a(23) =137472a(24) =270528a(25) =516720a(26) =863088a(27) =1710816a(28) =3173856a(29) =4836672