Final answer:
The recursive formula for the number of vertices in the graph Gt can be derived using the given equation n² = 2[n + 3 + .... + (2n - 3) + n].
Step-by-step explanation:
The recursive formula for the number of vertices nt in the graph Gt from the Kelly and Kelly proof of Proposition 5.25 can be derived using the given equation: n² = 2[n + 3 + .... + (2n - 3) + n].
To find the recursive formula, we can rewrite the equation as n² = 2[n + 3 + .... + (n + n)].
Next, we can simplify the expression by adding the terms inside the brackets and combining like terms, which gives us the recursive formula nt = 2(n + 3 + .... + n).