Find the value V of the Riemann sum $\displaystyle {V}={\sum_{{{k}={1}}}^{{n}}}{f{{\left({c}_{{k}}\right)}}}\ \Delta{x}_{{k}}$

for the function $\displaystyle {f{{\left({x}\right)}}}={2}^{{x}}$ using the partition P = { 1, 3, 4, 7 }, where the $\displaystyle {c}_{{k}}$ are the midpoints of the partition intervals.

V =