turtle.forward()
right = true

function turn() 
    if right then
        turtle.turnRight()
    else
        turtle.turnLeft()
    end
end

for row = 1, 5 do
    for block = 1, 16 do
        turtle.placeDown()
        turtle.forward()
    end
    turn()
    turtle.forward()
    turn()
    turtle.forward()
    right = not right
end