Lucas(3n+2) = Fibonacci(3n+1) + Fibonacci(3n+3).

Terms

a(0) =3a(1) =11a(2) =47a(3) =199a(4) =843a(5) =3571a(6) =15127a(7) =64079a(8) =271443a(9) =1149851a(10) =4870847a(11) =20633239a(12) =87403803a(13) =370248451a(14) =1568397607a(15) =6643838879a(16) =28143753123a(17) =119218851371a(18) =505019158607