https://www.cnblogs.com/EasonJim/p/8315939.html

#!/bin/bash  
  
for((i=1;i<=10;i++));  
do   
echo $(expr $i \* 3 + 1);  
done

#!/bin/bash  
  
for i in $(seq 1 10)  
do   
echo $(expr $i \* 3 + 1);  
done  

#!/bin/bash  
  
for i in {1..10}  
do  
echo $(expr $i \* 3 + 1);  
done  

#!/bin/bash  
  
awk 'BEGIN{for(i=1; i<=10; i++) print i}'