What if the founders don't seek investment from Sequoia after the initial YC investment. In this case Sequoia would never have had the opportunity to pass. I

What if the founders don't seek investment from Sequoia after the initial YC investment. In this case Sequoia would never have had the opportunity to pass. I imagine there is no 'you have to request funding from Sequoia' clause that comes with the YC money. In fact, from my understanding, you don't have to take any investment in the future if you so choose.