a(2n) = 2^(2n), a(2n+1) = 2^(2n+1) + a(n).

Terms

a(0) =1a(1) =3a(2) =4a(3) =11a(4) =16a(5) =36a(6) =64a(7) =139a(8) =256a(9) =528a(10) =1024a(11) =2084a(12) =4096a(13) =8256a(14) =16384a(15) =32907a(16) =65536a(17) =131328a(18) =262144a(19) =524816a(20) =1048576a(21) =2098176a(22) =4194304a(23) =8390692a(24) =16777216a(25) =33558528a(26) =67108864a(27) =134225984a(28) =268435456a(29) =536887296