In each of the following questions, a number series is given. After the series a number is given following by $\left(\mathrm{a}\right), \left(\mathrm{b}\right), \left(\mathrm{c}\right), \left(\mathrm{d}\right)$ and $\left(\mathrm{e}\right)$. You have to complete the series with the number given, following the sequence of the original series and answer the question that follow the series.

$\begin{array}{ccccccc}2& 4.5& 11& 30& 93& 312& 1136\\ 1& (\mathrm{a}) & (\mathrm{b}) & (\mathrm{c}) & (\mathrm{d}) & (\mathrm{e}) & (\mathrm{f}) \end{array}$

What will come in place of $\left(\mathrm{b}\right)$?