Problem Statement

Write a program which counts up from   1,   displaying each number as the multiplication of its prime factors. For the purpose of this task,   1   (unity)   may be shown as itself.

2   is prime,   so it would be shown as itself.       6   is not prime;   it would be shown as

2 × 3

{\displaystyle 2\times 3}

. 2144   is not prime;   it would be shown as

2 × 2 × 2 × 2 × 2 × 67

{\displaystyle 2\times 2\times 2\times 2\times 2\times 67}

.

Let's start with the solution:

PROC PrintFactors(CARD a)
  BYTE notFirst
  CARD p

  IF a=1 THEN
    PrintC(a) RETURN
  FI

  p=2 notFirst=0
  WHILE p<=a
  DO
    IF a MOD p=0 THEN
      IF notFirst THEN
        Put('x)
      FI
      notFirst=1
      PrintC(p)
      a==/p
    ELSE
      p==+1
    FI
  OD
RETURN

PROC Main()
  CARD i

  FOR i=1 TO 1000
  DO
    PrintC(i) Put('=)
    PrintFactors(i)
    PutE()
  OD
RETURN