Naming convention here is a bit tricky. Gene density as defined by Dr. Dekhtyar is # of genes / length (in nucleotides) of the segment.  This is clearly not what we are calculating here.  This appears to be (correct me if I'm wrong, please) the number of genes times the average size of the genes, over the total number of nucleotides.

Which would be the sum of each gene's size over the total number of nucleotides, or the total genetic code/the sequence.