let-give-n-p-from-N-2-and-1-p-n-prove-that-k-0-p-C-n-k-C-n-k-p-k-2-p-C-n-p-

Question Number 29163 by abdo imad last updated on 04/Feb/18

l e t g i v e (n, p) f r o m N^{2} a n d 1 ⩽ p ⩽ n p r o v e t h a t

\sum_{k = 0}^{p} C_{n}^{k} C_{n - k}^{p - k} == 2^{p} C_{n}^{p} .