First and Second differences

When we have sequences of related numbers we can determine the relations ships between these numbers by finding the differences between the elements in the sequence. If the differences between the numbers are constant, the sequence is a linear equation.

A linear sequence has a seed, a number from which the sequence begins, in the following formula the seed can be understood as b. The sequence increases by an equal value every iteration, if the sequence increase by 7 each time, then this is the common difference, or in the following equation represented by a. n stands for the term number. The 1st term is n = 1 .... and so the seed is not the 1st value of the iteration but the 1st term minus the common difference.