Let D be a BIBD with parameters (b,v,r,3,1). Prove that either v=6i+1 or v=6i+3 for some non-negative integer i. BIBD stands for a Balanced Incomplete Block Design
My work, theorem states that bk=vr in BIBD, which I can use to solve the problem. my basic step would be solving the equation with given v=6i+1.
Any suggestion on how to go about doing it?