primes in lua

primes.lua

function get_primes (n) 
  compo={}
  primes={}
  for i=2,n do
    if not compo[i] then
      primes[i]=true
      for j=i*2,n,i do
        compo[j]=true
      end
    end
  end
  return primes
end

for k,v in pairs(get_primes(10000)) do
  print(k)
end

t0=os.clock()
for i=0,500 do
  get_primes(10000)
end
print(os.clock()-t0)