permutations/combinations

Hello!

I'm trying to write a program that outputs the possible combinations of a se
t of numbers, but I can't seem to get it right.. 

In a list of 1-2-3, the program only outputs 1-2-3.
It should be
1-2-3
1-3-2
2-1-3
2-3-1 etc... 

Any suggestions? The code:

MODULE div

INTEGER, PARAMETER :: usedmax = 3
LOGICAL, DIMENSION(usedmax) :: used
INTEGER, DIMENSION(usedmax) :: choice

CONTAINS

RECURSIVE SUBROUTINE Useit()
INTEGER :: i, j

   DO i = 1, usedmax, 1
      IF (.NOT. used(i)) then
         used(i) = .TRUE.
         WRITE (*,*) 'made choice', choice(i)
         CALL UseIt()
         RETURN
      ENDIF
   ENDDO
RETURN
   
END SUBROUTINE UseIt

SUBROUTINE Init
IMPLICIT NONE
   INTEGER :: i
   DO i = 1, usedmax, 1
      used(i) = .false.
      choice(i) = i
   ENDDO
   RETURN
   
END SUBROUTINE init
END MODULE

PROGRAM main
USE div
IMPLICIT NONE
   CALL Init
   CALL UseIt()
   STOP
END PROGRAM main