Prime number functions done in Lua. First function determines if a number is prime, while the second function print to screen the first 'n' prime numbers. View comments for more information.

Prime.lua

---Function to determine if a number is a prime number
function isPrime(num)
  if num <= 0 then
		print("Number must be a positive integer greater than zero")
		return false
	elseif num == 1 then return true end
	--[[Prime number is divisable by itself and one,
		so we check for other factors between the prime number and one. (1 < x < num)
	]]
	for x = num-1,2,-1 do
		if (((num % x) == 0) and x > 1) then
			return false
		end
	end

	return true
end

--Funtion to print the first 'n' prime numbers
function printPrime(n)
	local count = 1
	local pnum = 1
	repeat
		if isPrime(pnum) then
			print(pnum)
			pnum = pnum + 1
			count = count + 1 -- count only incremented when a prime number is found
		else
			pnum = pnum + 1
		end
	until(count > n)
end

--***Test Section***
print(isPrime(1)) --True
print(isPrime(-2)) --Number must be a positive integer greater than zero; False
print(isPrime(51)) --False
print(isPrime(3037)) --True
printPrime(10)
--[[
Output:
	1
	2
	3
	5
	7
	11
	13
	17
	19
	23
]]