말씀대로 고치니 table도 필요없군요.

function permuteCases(word)
    local word = string.lower(word)
    local padding = "%0" .. #word .. "d"

    tex.print("\\begin{ttfamily}")
    for decimal=0, 2^(#word)-1 do
        local binary = ""
        while decimal > 0 do
            local remainder = decimal % 2
            binary = tostring(remainder) .. binary
            decimal = math.floor(decimal / 2)
        end
        binary = string.format(padding, binary == "" and "0" or binary)
        local perm = ""
        for j=1, #word do
            if string.sub(binary, j, j) == "0" then
                perm = perm .. string.sub(word, j, j)
            else
                perm = perm .. string.upper(string.sub(word, j, j))
            end
        end
        tex.print(perm .. "\\quad")
        if (decimal+1) % #word == 0 then
            tex.print("\\newline")
        end
    end
    tex.print("\\end{ttfamily}")
end