`DiscretePlot` gives wrong results nested function in ``First`` or ``Last``

[rocky]

Description

Using QuotientRemainder inside a DiscretePlot is giving incorrect plots

How to Reproduce and Output Given

Try these examples:

DiscretePlot[First[QuotientRemainder[n, 5]], {n, 0, 40}]
DiscretePlot[Last[QuotientRemainder[n, 5]], {n, 0, 40}]

See output below for what we get.

Expected behavior

Analog of what ListLinePlot shows. See also https://wolfram.com/xid/0bto17b3nqju-0nx3r

Workarounds

Use ListLinePlot? That seems to work.

Priority

Additional context

Note that there is a different weirdness around using Quotient. That may or may not be related to a bug in DiscretePlot. See #1722

[rocky]

The bug was erroneously using N[] in evaluating the plot function. I suspect this was a faulty "optimization".

In our example, N[Last[QuotientRemainder[n, 5]]] returns 5. as the function to evaluate, when it should be left as a symbolic expression.