a(n) = Sum_{k=1..n} 2^(n mod k).

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =10a(5) =10a(6) =20a(7) =22a(8) =37a(9) =40a(10) =80a(11) =72a(12) =144a(13) =158a(14) =278a(15) =283a(16) =566a(17) =548a(18) =1096a(19) =1120a(20) =2106a(21) =2162a(22) =4324a(23) =4210a(24) =8389a(25) =8584a(26) =16650a(27) =16772a(28) =33544a(29) =33194