Thread: how to count elements View Single Post
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P: 4,499
 Quote by Norwegian Now, you have posted four times in this thread, and you have yet to inform us what those entries are. In particular, what is the entry in row i, colomn j?
It's i*j

Here's a small matrix example of what he's talking about

$$\left( \begin{array}{ccc} 1*1 & 1*2 & 1*3 \\ 2*1 & 2*2 & 2*3 \\ 3*1 & 3*2 & 3*3 \end{array} \right)$$

The question can be rephrased as: $$u(n) = | \{ a*b \|\ a\leq n,\ b\leq n \}|$$
calculate u(n).