i need Solution

The sequence of numbers 1, 1, 3, 5, 11, 21, 43, 85, 171, 341, .. is like the original Fibonacci sequence except that it is defined recursively by f1 = 1, f2 = 1, and fn+1 = fm + 2fn- for n 2 2. Use strong induction to prove that fn = = [2" + (-1)"+1] With that formula, use your calculator to find f2s