Floor(sqrt(2*3^n)).

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =12a(5) =22a(6) =38a(7) =66a(8) =114a(9) =198a(10) =343a(11) =595a(12) =1030a(13) =1785a(14) =3092a(15) =5357a(16) =9278a(17) =16071a(18) =27835a(19) =48213a(20) =83507a(21) =144639a(22) =250523a(23) =433919a(24) =751571a(25) =1301759a(26) =2254713a(27) =3905277a(28) =6764139a(29) =11715833