To add to this, a "tl;dr" is only useful if written by people who actually read the whole article. That is, written by people who did not apply "tl;dr" themselves.

In this particular case, the article clearly says:

> The array will contain 4294967295 integers, each with the size of four bytes, taking up 17179869180 bytes in total.

Later, the article again stresses again that you have to multiply by four:

> having the size of 10000 integers, that is, 40000 bytes

It's really hard to imagine how somebody who actually did read the article could have missed that.