def fn.fib%(n%)
  p1% = 0
  p2% = 1
  if n% = 0 then \
    f% = 0 \
  else \
    for i% = 1 to n%
      f% = p1% + p2%
      p2% = p1%
      p1% = f%
    next i%
  fn.fib% = f%
  return
fend

print "First 20 Fibonacci numbers:"
for k% = 1 to 20
   print fn.fib%(k%);
next k%

end