I'll have a go at this:
Mega is, as we've discussed in previous questions, a two (2) inside of a circle.
This notation, known as Steinhaus-Moser notation, makes the circle synonymous with a pentagon
As stated in the linked article, "a number n in a triangle means nn."
'a number n in a square is equivalent to "the number n inside n triangles, which are all nested."'
'a number n in a pentagon is equivalent with "the number n inside n squares, which are all nested."'
So you could claim that, since the circle is operationally equivalent to the pentagon, the pattern is an increasing number of sides of the enclosing shape.
I don't know how to do the fancy number shit*, so if anybody wants to give me a hand there, feel free.
* but I am a font of technical terminology such as this