A sum of the terms of an arithmetic Sequence, which is a list of Numbers with a constant difference.
If the first and last number of the sequence are known, the sum
If the first number and the constant difference are known, then the sum
A sum of the terms of an arithmetic Sequence, which is a list of Numbers with a constant difference.
If the first and last number of the sequence are known, the sum
If the first number and the constant difference are known, then the sum