Fine's Equation

$$\prod_{n=1} {(1-q^{2n})(1-q^{3n})(1-q^{8n})(1-q^{12n})\over (1-q^n)(1-q^{24n})} = 1+\sum_{N=1} E_{1,5,7,11}(N;24)q^N,$$

where $E$ is the sum of the Divisors of $N$ Congruent to 1, 5, 7, and 11 (mod 24) minus the sum of Divisors of $N$ Congruent to $-1$, $-5$, $-7$, and $-11$ (mod 24).

See also q-Series