Fibonacci(n) - (-1)^n.

Terms

a(0) =2a(1) =0a(2) =3a(3) =2a(4) =6a(5) =7a(6) =14a(7) =20a(8) =35a(9) =54a(10) =90a(11) =143a(12) =234a(13) =376a(14) =611a(15) =986a(16) =1598a(17) =2583a(18) =4182a(19) =6764a(20) =10947a(21) =17710a(22) =28658a(23) =46367a(24) =75026a(25) =121392a(26) =196419a(27) =317810a(28) =514230a(29) =832039