Today's mentalfloss.com Think Thursday Brain Game challenge is one we first offered, oh, about four years ago. Let's see if it's improved with age:

What's the next number in this sequence?

2, 3, 10, 12, 13, 20, 21, ?, ...

Here is my SOLUTION. 

SOLUTION:

22. They're the whole numbers that, when spelled out, begin with the letter "T."

Thanks for playing!