Speed of a graph property ($|{\mathcal{P}}_n|$)

The speed counts the labelled graphs with a given property on vertex set $[n]$. For proper unbounded hereditary graph properties, its base-two logarithm has leading term $(1-1/r)\left(\genfrac{}{}{0ex}{}{n}{2}\right)$, where $r$ is the property's colouring number.