How can I make this random number generator more random?

The problem with my current system is that a pattern occurs when the player first rolls the dice, and then doesn't change until they change the number of sides of the dice.

For example, when I first load the game, the game defaults to 1d6. So when I roll the dice, let's say that the outcome was 6. No matter how many times I roll the dice after that, or how many dice I roll, the result is ALWAYS 6 until I change the sides, as you can see below.

sides = 6
numdice = 1
rolls = {}


function rollthedice()
    for i = 1, numdice do
        math.randomseed(tick())
        table.insert(rolls, math.random(1,sides))
    end
    print("Rolled "..numdice.." dice with "..sides.." sides!")
    print(table.concat(rolls, ' '))
end

And here's my output:

Rolled 1 dice with 6 sides! 6 Rolled 3 dice with 6 sides! 6 6 6 6 Rolled 3 dice with 14 sides! 6 6 6 6 13 13 13 Rolled 1 dice with 14 sides! 6 6 6 6 13 13 13 13 Rolled 1 dice with 14 sides! 6 6 6 6 13 13 13 13 13 Rolled 1 dice with 14 sides! 6 6 6 6 13 13 13 13 13 13

Obviously I'd like to eliminate these patterns, if at all possible. I want this to be truly random, or as close as I can easily and feasibly get.