A seven digit positive octal integer X is constituted by arranging the nonzero octal digits 1-7 in some order, so that:

• The octal number formed by the first two digits is divisible by 2.
  
• The octal number formed by the first three digits is divisible by 3.
  
• The octal number formed by the first four digits is divisible by 4.
• and, so on up to seven digits...

Determine all possible value(s) that X can assume.