F(2n) = bisection of Fibonacci sequence: a(n) = 3*a(n-1) - a(n-2).

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =21a(5) =55a(6) =144a(7) =377a(8) =987a(9) =2584a(10) =6765a(11) =17711a(12) =46368a(13) =121393a(14) =317811a(15) =832040a(16) =2178309a(17) =5702887a(18) =14930352a(19) =39088169a(20) =102334155a(21) =267914296a(22) =701408733a(23) =1836311903a(24) =4807526976a(25) =12586269025a(26) =32951280099a(27) =86267571272a(28) =225851433717a(29) =591286729879