Why would I see no bands in DNA gel electrophoresis of red blood cells?
It is a trick question. Red Blood Cells (RBC) are anucleated in mammals. You are not going to be able to extract anything about chromosome 1 from RBC.

By the way, if you want to know how they got from 29 alleles to 435 possible combinations (in a diploid), you just have to do 29 + 28 + 27 + ... + 1 = 435.