**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...

**X**can assume.