If nCr=Cr then C0+(C0+C1)+(C0+C1+C2)+....+(C0+C1+.....+Cn) =
(n+2)2n-1
C0+(C0+C1)+(C0+C1+C2)+....+(C0+C1+.....+Cn) =
n.C0+(n−1)C1+(n−2)C2+.......+Cn=
C0+2C1+3C2+......+n.Cn[∴nCr=nCn−r]
= (n+2) 2n−1[∴a.C0+(a+d)C1+(a+2d)C1+......+(a+(n−1)d)Cn=(2a+nd)2n−1 ]