a(n) = Sum_{k=1..n} floor(binomial(n,k)/k).

Terms

a(0) =0a(1) =1a(2) =2a(3) =4a(4) =8a(5) =14a(6) =23a(7) =41a(8) =73a(9) =131a(10) =232a(11) =418a(12) =758a(13) =1388a(14) =2558a(15) =4742a(16) =8837a(17) =16547a(18) =31111a(19) =58705a(20) =111133a(21) =210996a(22) =401645a(23) =766367a(24) =1465416a(25) =2807595a(26) =5388705a(27) =10359733a(28) =19946714a(29) =38459504