This is LaTeX code:

[latex]
\begin{aligned}
 \sum_{i\in\omega\cdot 2} (i+\omega\cdot 2)
 & = \sum_{i\in\omega} (i+\omega\cdot 2) + \sum_{i\in\omega} (\omega+i+\omega\cdot 2) \\
 & = \sup_{n\in\omega}\sum_{i\in n} (i+\omega\cdot 2) + \sup_{n\in\omega}\sum_{i\in n} (\omega+i+\omega\cdot 2) \\
 & = \sup_{n\in\omega}(\omega\cdot 2\cdot n)+\sup_{n\in\omega}(\omega\cdot 3\cdot n) \\
 & = \omega^2+\omega^2 \\
 & = \omega^2\cdot 2
\end{aligned}
[/latex]