Number of subsets of {1,2,...,n} whose sum is semiprime (cf. A001358, A064911).

Terms

a(0) =0a(1) =0a(2) =2a(3) =6a(4) =13a(5) =25a(6) =47a(7) =92a(8) =184a(9) =367a(10) =721a(11) =1416a(12) =2769a(13) =5407a(14) =10662a(15) =21135a(16) =41866a(17) =83220a(18) =166617a(19) =334852a(20) =670725a(21) =1334868a(22) =2650263a(23) =5280475a(24) =10567613a(25) =21145411a(26) =42103939a(27) =83382359a(28) =164843079a(29) =326791838