a(n) = Fib(3*n)^2 - 2*Fib(3*n) + 4*Fib(3*n+1) + 5, where Fib = A000045.

A049440

a(n) = Fib(3*n)^2 - 2*Fib(3*n) + 4*Fib(3*n+1) + 5, where Fib = A000045.

Terms

    a(0) =9a(1) =17a(2) =105a(3) =1313a(4) =21385a(5) =374833a(6) =6688617a(7) =119863873a(8) =2150198793a(9) =38580909137a(10) =692294282601

External references