mathjax.js missing in html with pure display equations

using only display equations in markdown cells:

\begin{equation}
y = mx + c
\end{equation}

mathjax isn't loaded. At least one instance of inline maths needs to be in the notebook ( $y = mx + c$ ) in order to prompt nbsphinx to insert the following into the generated html:

<script async="async" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.7/latest.js?config=TeX-AMS-MML_HTMLorMML"></script>
<script type="text/x-mathjax-config">MathJax.Hub.Config({"TeX": {"equationNumbers": {"autoNumber": "AMS", "useLabelIds": true}}, "tex2jax": {"inlineMath": [["$", "$"], ["\\(", "\\)"]], "processEscapes": true, "ignoreClass": "document", "processClass": "math|output_area"}})</script>

spatialaudio / nbsphinx

mathjax.js missing in html with pure display equations #550