Why does my plot of the Blackman window not match everyone else's in literature?
There is a missing $2\times$ factor inside the second cosine, and you get a centered $201$ point windows with the change of variable $x-100$. See at Wolfram:

$$ 0.42 - 0.5*\cos\left(2\pi\frac{x-100}{200}\right) + 0.08 \cos\left(4\pi\frac{x-100}{200}\right)\,.$$