The sum of the sequence of consecutive numbers from 1 to n is given by the formula:
\[ S(n) = \frac{n(n+1)}{2} \]
This is a quadratic polynomial. When we go through the process of calculating differences of a polynomial, we find that:
- The 1st differences (which are the differences between consecutive values of the function) are linear.
- The 2nd differences (which are the differences of the 1st differences) are constant.
Since \(S(n)\) is a quadratic function, the constant value appears in the 2nd differences.
Therefore, the correct response is:
2nd differences