identification division.
       program-id. mixed.
      * Thema Polyome: aus
      * gemischten Termen 
      * entstehen quadratische
       author. "JD".
       date-written. 1.4.2009.
       date-compiled.
       data division.
       working-storage section.
         77 xn        pic S9(8)V99 comp.
       linkage section.
         77 x1        pic S9(8)V99 comp.
         77 x2        pic S9(8)V99 comp.
       procedure division.
         display "start"
         move 0 to xn
         perform until xn>=0
           compute x1=x1*x2 + 2
           compute x2=x1*x2
           add x1 x2 to xn
         end-perform
         display "done, xn="xn.
        end-program mixed.