a(n) = number of subsets of {1,2,...,n} that contain more nonprimes than primes.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =5a(5) =6a(6) =22a(7) =29a(8) =93a(9) =256a(10) =638a(11) =1024a(12) =2510a(13) =4096a(14) =9908a(15) =22819a(16) =50643a(17) =89846a(18) =199140a(19) =354522a(20) =784626a(21) =1695222a(22) =3593934a(23) =6690448a(24) =14198086a(25) =29703676a(26) =61450327a(27) =126025204a(28) =256737233a(29) =500351356