local function powers(n)
    local i = 0
    while true do
        coroutine.yield(i ** n)
        i += 1
    end
end

local function squares_not_cubes()
    local cosq = coroutine.create(powers)
    local cocu = coroutine.create(powers)
    local cube = 0
    while true do
        local _, square = coroutine.resume(cosq, 2)
        while cube < square do
            _, cube = coroutine.resume(cocu, 3)
        end
        if cube != square then coroutine.yield(square) end
    end
end

local co = coroutine.create(squares_not_cubes)
local count = 0
while count < 30 do
    local _, square = coroutine.resume(co)
    count += 1
    if count > 20 then io.write($"{square} ") end
end
print()