If 2nC3:nC2::44:1, the value of n is
The value of C01.3−C12.3+C23.3−C34.3+⋯+(−1)nCn(n+1).3 is
The value of 1.C1+3.C3+5.C5+7.C7+.... whereC0,C1,C2.....Cn are binomial coefficients in the expansion of (1+x)n is: