The formula you provided for the sum of the first n consecutive numbers is actually given by:
\[ S(n) = \frac{n(n+1)}{2} \]
This is a quadratic polynomial in \( n \).
To find which level differences of this polynomial are constant, we consider the differences:
- First differences: Calculate \( S(n+1) - S(n) \).
- Second differences: Calculate the first differences of the first differences.
- Third differences: Calculate the first differences of the second differences.
- Fourth differences: Continue this process.
Since \( S(n) = \frac{n(n+1)}{2} \) is a quadratic polynomial, the first differences will not be constant, but the second differences will be constant.
Thus, the answer is:
2nd differences.