Follow
leading questions toward a solution
If aₙ is a perfect square, some integer sₙ exists such that sₙ² = aₙ.
Can sₙ be even? If so, you could write it as 2s'ₙ for some integer s'ₙ. What happens when you try to solve (2s'ₙ)² = aₙ since aₙ is always odd?
Can sₙ be odd? If so, you could write it as 2s'ₙ + 1 for some integer s'ₙ. What happens when you try to solve (2s'ₙ + 1)² = aₙ since aₙ is of the form 100 * aₙ₋₁ + 11?
