Show that $$ (1+q)(1+q^3)(1+q^5) \cdots = 1+ \sum_{k=1}^\infty \frac{q^{k^2}}{(1-q^2)(1-q^4)(1-q^6) \cdots (1-q^{2k})}.$$
How would one proceed combinatorially. What I know is that the left-hand side counts Ferrers diagrams with distinct odd parts and the right counts self-conjugate partitions with Durfee number k.