Degree Correlation Function

In a network, for nodes of degree \( k = 3 \), the conditional degree distribution of their neighbors is given by

\[p(k' = 1 \mid k = 3) = 0.50\]

\[p(k' = 2 \mid k = 3) = 0.30\]

\[p(k' = 5 \mid k = 3) = 0.20\]

What is the value of \( k_{nn}(3) \), i.e., the average degree of the neighbors of nodes with degree 3?

1. 1.8
2. 2.1
3. 3.0
4. 3.5
5. None of the above.

Original idea by Jonas Henrique Ribeiro Paula