I've found this Order of Differences problem, which I can't find information on.
This may be recurrent on sequences, maybe I got the name of it wrong.
We are to find the sum of the first 7 terms in this sequences.
The solution says something about T(n) being of the second degree.
3 > 1
6 > 1
10 > 1
Then later it states
The 1, 3 and 6 part is related to the number of points in the triangle but what does the other part means?
This seems like a complex sequence at first.
Can someone help?