n(n+1)/2 what is a pattern that I can use for the first 3 figures using this equation

n(n+1)/2 what is a pattern that I can use for the first 3 figures using this equation

 

Well, why don't start with 1 and substitute it for n. And if you did that, what do you get?: n(n+1)/2=1(1+1)/2=1. How about 2: 2(2+1)/2=3. How about 3:      

 3(3+1)/2=6. Is it clear to you what the pattern is for the first 3 figures?: They are:

1, 3, 6. Beyond that, the patten does not hold. If you try 4, you will get 10....and so on.

Yes, the pattern does still hold.

You just have not thought of the right pattern :))