How to print a sequence of characters with single space or tabs when the printf command is used in this way ?

Code:
#!/bin/bash
for ((x=1;x<=1391;x+=1)); 
do
echo `printf "%08d" $x`.pdf ;
done
I want the bash to print the output like this

Code:
00000001.pdf 00000002.pdf 00000003.pdf  .......