Number of subsets of {1..n} containing all of their integer quotients.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =9a(5) =17a(6) =25a(7) =49a(8) =73a(9) =145a(10) =217a(11) =433a(12) =553a(13) =1105a(14) =1657a(15) =2593a(16) =3937a(17) =7873a(18) =10057a(19) =20113a(20) =26689a(21) =42321a(22) =63481a(23) =126961a(24) =154801a(25) =309601a(26) =464401a(27) =737569a(28) =992161a(29) =1984321