a(n) = number of nonempty subsets S of {1,2,...,n} such that (number of primes in S) <= (number of nonprimes in S).

A369781

a(n) = number of nonempty subsets S of {1,2,...,n} such that (number of primes in S) <= (number of nonprimes in S).

Terms

    a(0) =0a(1) =1a(2) =2a(3) =3a(4) =10a(5) =15a(6) =41a(7) =63a(8) =162a(9) =381a(10) =847a(11) =1485a(12) =3301a(13) =5811a(14) =12910a(15) =27823a(16) =58650a(17) =109293a(18) =230963a(19) =430103a(20) =910595a(21) =1898711a(22) =3913703a(23) =7507637a(24) =15505589a(25) =31746650a(26) =64574876a(27) =130712028a(28) =263644132a(29) =520381365

External references