» Checking For Sequences Within A Sorted List

Problem:

List1 (column A) is a series of numbers that has been sorted in ascending order.
We want to create a formula that will check whether each number is part of a consecutive sequence.

Solution:

Use the IF and OR functions as shown in the following formula:
=IF(OR((A2+1=A3),(A2-1=A1)),"Sequential","Not Sequential")

Example:


List1___Result
1_______Sequent
2_______Sequent
4_______Not Sequent
6_______Sequent
7_______Sequent
9_______Not Sequent
11______Sequent
12______Sequent

Screenshot // Checking For Sequences Within A Sorted List