a(n) = Fibonacci(4*n + 2)
- a(n-1) = ((7+3*sqrt(5))^n - (7-3*sqrt(5))^n + 2*((7+3*sqrt(5))^(n-1) - ((7-3*sqrt(5))^(n-1)))) / (3*(2^n)*sqrt(5))
- a(n) = ((3 + sqrt(5))^(1 + 2*n) - (3 - sqrt(5))^(1 + 2*n)) / (2^(1 + 2*n)*sqrt(5))
https://oeis.org/A033890 - a(n) = 7*a(n-1) - a(n-2), n > 1; a(0)=1, a(1)=8
https://oeis.org/A033890/b033890.txt