With (Mathematica's QPochhammer[a,q]), the expressions and represent Roger–Ramanujan and Roger–Ramanujan , also representable as and , using Mathematica's notation for continued fractions (the ContinuedFractionK[] function). In 1919, months before his death, Ramanujan wrote down various elegant results for this function in what became the "lost notebook."

Ramanujan claimed that many equations like can be expressed in terms of radicals [1]. This notebook collects many of these results.