Universal Cup Judging System
Universal Cup
User profile
ucup-team5027
Usergroup
Default
Organization
Southern University of Science and Technology
Motto
Benson's Identity: $$\dbinom{n}{2k}2^{2k}=\sum\limits_{i=0}^k(-1)^i\dbinom{n}{i}\dbinom{2n-2i}{2k-2i}$$