Calculating the probability of a graph being Erdos-Renyi

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Given an undirected, unweighted graph with |V| = 11 and |E|= 19 and given probability p=0.5 I have to calculate the probability of the graph being generated using the Erdos-Renyi Model. I applied the following formula: $$p^{|E|} * (1-p)^{\binom n 2-|E|}$$ but the answer i get it's not correct (I have a list of possible answers and my result is not in those)

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Consider the graphs on numbered vertices. When $p=1/2$, every graph is equiprobable, so the probability to get a a particular graph is $1/2^{n \choose 2}$. Now if you want some isomorphism class $G$ (a graph on undistinguished vertices) you just erase the labels, which gives you a factor of $aut(G)$, the number of automorphisms of $G$.