Rename "n" to "j", so it does not conflict with the "2^n" from the number of buckets equation
Added simplification for bucket index equation

This patch adds a simplification for the bucket index calculation,
taking the equation for the number of buckets of the hashtable into
account. It adds a label to the latter for referencing purposes.
Merge pull request #216 from matthiasbeyer/add-paper_bucket_indexing_algorithm_simplification

Added simplification for bucket index equation