a(n) = 2^floor(n/2).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =4a(5) =4a(6) =8a(7) =8a(8) =16a(9) =16a(10) =32a(11) =32a(12) =64a(13) =64a(14) =128a(15) =128a(16) =256a(17) =256a(18) =512a(19) =512a(20) =1024a(21) =1024a(22) =2048a(23) =2048a(24) =4096a(25) =4096a(26) =8192a(27) =8192a(28) =16384a(29) =16384