a(1)=1; then successively add 1, divide by 2, add 2 and then total up the last 4 terms.

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =7a(5) =8a(6) =4a(7) =6a(8) =25a(9) =26a(10) =13a(11) =15a(12) =79a(13) =80a(14) =40a(15) =42a(16) =241a(17) =242a(18) =121a(19) =123a(20) =727a(21) =728a(22) =364a(23) =366a(24) =2185a(25) =2186a(26) =1093a(27) =1095a(28) =6559a(29) =6560