Well it is wrtitten in LaTex, so I opened the [LaTex Formula] box and copied it in.
This is what it is supposed to look like.
$$4\pi r^2$$ is the surface area of a sphere.
BUT I really don't know what this is about.
One of our higher level mathematicians might be able to help you more. 
$$L_s=\int_o^{\infty} L_{\lambda} d\lambda = 4\pi R_s^2 \int_0^{\infty} F_{\lambda} d\lambda$$
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