Yes, but it requires you to have great talent in mathematics, and then you will publish your academic research in some authoritative mathematical journals. Many authorities will see that they may be invited to graduate school. However, as you know, it is still very difficult to write a new mathematical research paper. If you have a strong talent in mathematics, it may come true. But if your talent is average, it is recommended to go to college, because you can have a tutor to discuss and study with many students.