a(1)=1, then a(n) = smallest number whose square is larger than 2*(a(n-1))^2.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =8a(5) =12a(6) =17a(7) =25a(8) =36a(9) =51a(10) =73a(11) =104a(12) =148a(13) =210a(14) =297a(15) =421a(16) =596a(17) =843a(18) =1193a(19) =1688a(20) =2388a(21) =3378a(22) =4778a(23) =6758a(24) =9558a(25) =13518a(26) =19118a(27) =27037a(28) =38237a(29) =54076