Question: How do I solve for a pointplot when it goes above a constant?

I have plotted in the same display a pointplot and a constant (a horizontal line)..

The worksheet is:

plot1 := plots[pointplot]([seq([r, 1 - combinat[numbperm](180000, r)/180000^r], r = 1 .. 1000)]);

plot2 := plot(0.25, r = 1 .. 1000);
display({plot1, plot2}, axes = boxed);

How do I solve for when the constant plot2 is less than plot1? I know at r=323 it goes above the threshold, but I don't know how to show this in an expression in Maple, and I've looked for several hours now, both Google search and on Maplesoft with no luck.

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