4 times the Lucas number A000032(n).

Terms

a(0) =8a(1) =4a(2) =12a(3) =16a(4) =28a(5) =44a(6) =72a(7) =116a(8) =188a(9) =304a(10) =492a(11) =796a(12) =1288a(13) =2084a(14) =3372a(15) =5456a(16) =8828a(17) =14284a(18) =23112a(19) =37396a(20) =60508a(21) =97904a(22) =158412a(23) =256316a(24) =414728a(25) =671044a(26) =1085772a(27) =1756816a(28) =2842588a(29) =4599404