Dad problems

Well, I am 20 years old and am desperately trying to connect with my father. No luck so far. I am his first child and he had me when he was 18/19. He divorced my mother when I was 1, but he has had me every other weekend since then and 4 weeks during the summer, and holidays. I come now to see him still and my other siblings. He talks to my 13 year old step brother all the time and my 8 year old sister, but completely ignores me when I try to talk to him. He literally acts like I am not there. It hurts my feelings so bad, idk what to do...