Observe the following group numbers - 1,1,5,11,19,29 1) Use an algebraic expression containing n to represent the nth number in this column. 2) is 2010 in this column? If yes, find out how many numbers are lower. If not, explain the reason

Observe the following group numbers - 1,1,5,11,19,29 1) Use an algebraic expression containing n to represent the nth number in this column. 2) is 2010 in this column? If yes, find out how many numbers are lower. If not, explain the reason

The general formula of this sequence is: n (n-1) - 1
2 〉 2010 is not included in this general term
The analysis is as follows:
-1=2×0-1
1=2×1-1
5=2×3-1
11=2×6-1
19=2×10-1
29=2×15-1
Then observe the number rule of each term multiplied by 2 as follows:
0=0
1=0 1
3=0 1 2
6=0 1 2 3
10=0 1 2 3 4
15=0 1 2 3 4 5
It can be seen from the above that it can be expressed by the first n terms and the formula n (n 1) / 2, that is, n (n-1) / 2
Bring it into the original formula
n(n-1)-1