<dl data-parsoid='{}'><dd data-parsoid='{}'><p typeof="mw:Extension/math" about="#mwtXX" data-parsoid='{}' data-mw='{"name":"math","attrs":{},"body":{"extsrc":"1^2 + 2^2 + \\cdots + n^2 = {n(n + 1)(2n + 1) \\over 6}"}}'>^?'"`UNIQ--postMath-00000001-QINU`"'^?</p></dd></dl>
Found when I parsed enwiki:Aryabhata on scandium and diffed PHP & JS output