a(n) = n + 2*cos((n*Pi)/3) + Lucas(n).

Terms

a(0) =3a(1) =4a(2) =5a(3) =10a(4) =17a(5) =26a(6) =37a(7) =54a(8) =83a(9) =132a(10) =211a(11) =336a(12) =535a(13) =856a(14) =1377a(15) =2222a(16) =3589a(17) =5798a(18) =9369a(19) =15146a(20) =24495a(21) =39624a(22) =64103a(23) =103708a(24) =167787a(25) =271468a(26) =439229a(27) =710674a(28) =1149881a(29) =1860530