Number of product-free subsets of {1..n}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =6a(5) =12a(6) =22a(7) =44a(8) =88a(9) =136a(10) =252a(11) =504a(12) =896a(13) =1792a(14) =3392a(15) =6352a(16) =9720a(17) =19440a(18) =35664a(19) =71328a(20) =129952a(21) =247232a(22) =477664a(23) =955328a(24) =1700416a(25) =2657280a(26) =5184000a(27) =10368000a(28) =19407360a(29) =38814720