arithmetic progression

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A sequence, such as the positive odd integers 1, 3, 5, 7, … , in which each term after the first is formed by adding a constant to the preceding term.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun analysis A sequence in which each term except the first is obtained from the previous by adding a constant value, known as the common difference of the arithmetic progression.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (mathematics) a progression in which a constant is added to each term in order to obtain the next term