SQL Server 2012: Using SEQUENCE

A sequence is a user-defined schema bound object that generates a sequence of numeric values according to the specification with which the sequence was created. The sequence of numeric values is generated in an ascending or descending order at a defined interval and can be configured to restart (cycle) when exhausted. Sequences, unlike identity columns, are not associated with specific tables. 

In this link you have a nice article about Using SEQUENCE in SQL Server 2012 by Vinod Kumar.

You can also read more about SEQUENCE at MSDN here: CREATE SEQUENCE (Transact-SQL)