Randomseed Please help a different type

Hi All
I have searched all the forums on Randomseed and cant seems to find anything similar to mine.
basically im making a card game and need to generate random numbers for the computer player between 1 and 13,but i keep getting thesame number every time the card game runs, the code i have at the moment is

math.randomseed(os.time()) -->Generates random numbers
for i = 1, 1 do
a = math.random(1,13)
print(‘The card i am Playing is =’, a )
table.remove(arrComputer, a)

end

Basically i have an array for the computer state containing 1 to 13, so each time the computer generates random card, it is removed from the array so it cannot be played twice.
Any help with be appreciated
Thanks in advance [import]uid: 104213 topic_id: 17707 reply_id: 317707[/import]