A Fielder sequence.

Terms

a(0) =1a(1) =3a(2) =4a(3) =11a(4) =21a(5) =42a(6) =71a(7) =131a(8) =238a(9) =443a(10) =815a(11) =1502a(12) =2757a(13) =5071a(14) =9324a(15) =17155a(16) =31553a(17) =58038a(18) =106743a(19) =196331a(20) =361106a(21) =664183a(22) =1221623a(23) =2246918a(24) =4132721a(25) =7601259a(26) =13980892a(27) =25714875a(28) =47297029a(29) =86992802