a(1) = 1; a(n+1) = round(sqrt(3)*a(n)).

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =9a(5) =16a(6) =28a(7) =48a(8) =83a(9) =144a(10) =249a(11) =431a(12) =747a(13) =1294a(14) =2241a(15) =3882a(16) =6724a(17) =11646a(18) =20171a(19) =34937a(20) =60513a(21) =104812a(22) =181540a(23) =314437a(24) =544621a(25) =943311a(26) =1633863a(27) =2829934a(28) =4901589a(29) =8489801