Beth Hierarchy

• ${\beth }_0={\aleph }_0$

• ${\beth }_{\alpha +1}=2^{{\beth }_{\alpha }}$

• ${\beth }_{\lambda }={\bigcup }_{\alpha <\lambda }{\beth }_{\alpha }$ for limit $\lambda$

• ${\beth }_1=2^{{\aleph }_0},{\beth }_2=2^{{\beth }_1}$