Let $\Omega=\mathbb{N}$. Specify the $\Theta=\left \{ \left \{ 4 \right \} ,2\mathbb{N}+1\right \}$ generated by $\sigma$-Algebra. where the set $2\mathbb{N}+1=\left \{ 2n+1 | n \in \mathbb{N} \right \}$ refers to all odd.
$\sigma(\Theta)=\{\{4\},\mathbb{N},2n+1,2n \setminus 4\}$
Is this right?