a(n) = 2*n*Fibonacci(n) + (-1)^n + 1.

Terms

a(0) =2a(1) =2a(2) =6a(3) =12a(4) =26a(5) =50a(6) =98a(7) =182a(8) =338a(9) =612a(10) =1102a(11) =1958a(12) =3458a(13) =6058a(14) =10558a(15) =18300a(16) =31586a(17) =54298a(18) =93026a(19) =158878a(20) =270602a(21) =459732a(22) =779286a(23) =1318222a(24) =2225666a(25) =3751250a(26) =6312438a(27) =10606572a(28) =17797418a(29) =29825282