a(n) = ceiling(sqrt(2*a(n-1)*a(n-2))), a(1) = a(2) = 1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =3a(5) =4a(6) =5a(7) =7a(8) =9a(9) =12a(10) =15a(11) =19a(12) =24a(13) =31a(14) =39a(15) =50a(16) =63a(17) =80a(18) =101a(19) =128a(20) =161a(21) =204a(22) =257a(23) =324a(24) =409a(25) =515a(26) =650a(27) =819a(28) =1032a(29) =1301