Comparison-test.tex -- Corrected typo theorem 2.7.5 proof part II (pg 60)

Update typo following request on forum thread_id=318
modified a_{2^n} + (2^n - 1) to a_{2^n} + (2^{n+1} - 1)
Merge pull request #24 from AlmeCap/Theorem2.7.5_proof_part2_typo

Comparison-test.tex - Corrected typo theorem 2.7.5 proof part II pg 60