a(n) = round(Product_{k=1..n} 1 + 2^2^(-k)).

Terms

a(0) =1a(1) =2a(2) =5a(3) =11a(4) =23a(5) =46a(6) =92a(7) =184a(8) =369a(9) =738a(10) =1477a(11) =2954a(12) =5909a(13) =11818a(14) =23637a(15) =47274a(16) =94548a(17) =189096a(18) =378193a(19) =756387a(20) =1512775a(21) =3025550a(22) =6051101a(23) =12102203a(24) =24204406a(25) =48408812a(26) =96817625a(27) =193635250a(28) =387270501a(29) =774541002