$\frac{1}{{1!(n - 1)\,!}} + \frac{1}{{3!(n - 3)!}} + \frac{1}{{5!(n - 5)!}} + .... = $
$\frac{{{2^n}}}{{n!}}$; for all even values of $n$
$\frac{{{2^{n - 1}}}}{{n!}}$; for all values of $n$ i.e., all even odd values
$0$
None of these
The value of $^{15}C_0^2{ - ^{15}}C_1^2{ + ^{15}}C_2^2 - ....{ - ^{15}}C_{15}^2$ is
The sum of the coefficients in the expansion of ${(1 + x - 3{x^2})^{2163}}$ will be
If $S_n =$$\sum\limits_{r = 0}^n {\frac{1}{{^n{C_r}}}} $ and $T_n =$$\sum\limits_{r = 0}^n {\frac{r}{{^n{C_r}}}} $ then $\frac{{{T_n}}}{{{S_n}}}$ is equal to
The coefficient of $x^{4}$ in the expansion of $\left(1+x+x^{2}+x^{3}\right)^{6}$ in powers of $x,$ is
The sum, of the coefficients of the first $50$ terms in the binomial expansion of $(1-x)^{100}$, is equal to