Number of subsets of {2...n} containing no prime indices of the elements.

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =10a(5) =16a(6) =24a(7) =48a(8) =84a(9) =144a(10) =228a(11) =420a(12) =648a(13) =1080a(14) =1800a(15) =3600a(16) =5760a(17) =11136a(18) =16704a(19) =31104a(20) =53568a(21) =90624a(22) =136896a(23) =269952a(24) =515712a(25) =862080a(26) =1708800a(27) =3171840a(28) =4832640a(29) =9325440