1.
If C0,C1,C2,,CnC_0, C_1, C_2, \ldots, C_n denote the binomial coefficients in the expansion of (1+x)n(1 + x)^n, then the value of C0+(C0+C1)+(C0+C1+C2)++(C0+C1++Cn1)C_0 + (C_0 + C_1) + (C_0 + C_1 + C_2) + \ldots + (C_0 + C_1 + \ldots + C_{n-1}) is