There&#x27;s even an explicit bijection that has a formula associated with it:<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Calkin%E2%80%93Wilf_tree" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Calkin%E2%80%93Wilf_tree</a>