C0+C12+C23+..+Cnn+1=
2n+1-1n+1
2n-1n+1
2nn+1
1n+1
C0+C12x+C23x2+…+Cnn+1xn=(1+x)n+1−1(n+1)x⇒C0+C12+C23+…+Cnn+1=2n+1−1n+1.