sum of the terms of an arithmetic sequence
- Let (`u_(n)`) be an arithmetic sequence of common difference 6, and of first term `u_(0)= 1`. Let S be the sum of `u_(4)` to `u_(20)`. S=`u_(4)`+`u_(5)`+`u_(6)`+`. . .`+`u_(20)`.
- Compute the number of terms in S.
- Compute S.
Course reminder : Numerical sequences