【题意】大家只要百度一下就好了吧，斐波那契数列还是那常见的呀···

#!bin/bash

bianliang=1;
result1=0;
result2=0;
result3=0;
count=0
while [ $bianliang -le 20 ]
do
 if [ $bianliang -eq 1 ]
 then
  let result1=1
  let count+=result1
  let result3=result1
 elif [ $bianliang -eq 2 ]
 then
  let result2=1
  let count+=result2
  let result3=result2
 else
  let result3=result1+result2
  let result1=result2
  let result2=result3
  let count+=result3
 fi
 echo "第$bianliang个的值为:$result3"
 let bianliang+=1
done
echo "前20项总和为:$count"