2. A sequence is defined by
$$\begin{aligned}
u _ { 1 } & = 1
u _ { n + 1 } & = 2 - 3 u _ { n } \quad n \geqslant 1
\end{aligned}$$
- Find the value of \(u _ { 2 }\) and the value of \(u _ { 3 }\)
- Calculate the value of \(\sum _ { r = 1 } ^ { 4 } \left( r - u _ { r } \right)\)
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