one row too much in proof of 65.2

[fredbok]

Typo location:

OpenLogic/content/methods/induction/induction-on-N.tex

Line 125 in 534a139

& = \frac{n(k+1) + 2(k+1)}{2} = {}\\

What is the typo:
The line contains n(k+1), mixing n and k

Proposed correction:
change n to k, i.e.
& = \frac{k(k+1) + 2(k+1)}{2} = {}\

[rzach]

Thanks!