a(1) = 1, a(n) = Sum_{k=1..n-1} Sum_{d|k} a(d).

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =16a(5) =33a(6) =71a(7) =143a(8) =295a(9) =594a(10) =1206a(11) =2413a(12) =4871a(13) =9743a(14) =19559a(15) =39138a(16) =78428a(17) =156857a(18) =314047a(19) =628095a(20) =1256809a(21) =2513693a(22) =5028594a(23) =10057189a(24) =20116979a(25) =40233975a(26) =80472823a(27) =160945945a(28) =321901713a(29) =643803427