The coefficient of xn in the polynomial (x+ 2nC0)(x+ 2nC2)⋯(x+ 2nC2n) is
Required coefficient of xn = 2nC0+ 2nC2+ 2nC4+⋯+ 2nC2n=22n2=22n−1
In the expansion of (1+x)n the sum of coefficients
of odd powers of x is