function perform(n)
  local bmax = math.floor(log(3,n))
  local cmax = math.floor(log(5,n))
  for c = 0, cmax do
    for b = 0, bmax do
      local a = 0
      while 2^a*3^b*5^c < n do
        print(2^a*3^b*5^c, a, b, c)
        a = a + 1
      end
    end
  end
end