It is the second biggest problem for famous teachers to measure and control class 38 of seventh grade mathematics. How to write the eighth question

The regularity of such problems is very important. It is important to understand how the first picture is put together first.

As shown in the figure, the first figure is seven chess pieces, consisting of six vertices of a hexagon and 1 center.

What is that? 1*6+ 1=7

Similarly, what about the second one? 3*6+ 1= 19

The third one? 6*6+ 1=37

The regularity came out? What are the general terms? 3*(n- 1)*6+ 1？ (? n & gt=2)

So what? The back is easier? Put the sixth pattern? N=6, substitution, solution? 9 1

Put the n-th pattern? Simplify, huh? 18n- 17