I don't like this. Not because I got it wrong, (which I did,) but because I can't imagine how I would have gotten it right. It is very, very, difficult to narrow down to "the numbers must be ascending" because you have to EXCLUDE so many patterns first. Even if you set out under the impression that the rule was just that the numbers must increase, you'd have a lot of work to do to show that the collection of tests you'd chosen couldn't match any other pattern that WOULD discriminate against an increasing pattern that you simply hadn't tried yet. In short, testing for "numbers have to go up" is very hard, so it is absurd to say that anyone has overlooked the simple answer; it was not a simple answer, it was a very difficult answer (to confirm.)