通过在while循环中交替值来增加变量

Question

i=297 
z=301
while [ $i -le 300 ] && [ $z -ge 301 ]
                    do 
findPeaks ~/ChIP-Seq/ExamChIP-Seq/TagDir/SRR1524"$i".fastq.gz.sam 
-style factor -center -o ~/ChIP-Seq/ExamChIP-Seq/PeaksFound/SRR1524"$i"_SRR1524"$z"peaks.txt 
-i ~/ChIP-Seq/ExamChIP-Seq/TagDir/SRR1524"$z".fastq.gz.sam
i=$(( $i +1))
echo "Peaks found for SRR1524$i with SRR1524$z"
                    done

我希望$ z每4个周期增加一次，同时在循环的每个周期增加$ i而不跳过$ z的任何值