8. A system comprising: a computer processor; and a memory containing instructions that, when executed cause the computer processor to: receive data identifying a set of seed content items and a sequential order for the set of seed content items, wherein the set of seed content items includes at least one seed content item included in a first content item playlist, and the sequential order indicates an order in which seed content items from the set of seed content items are ordered to be performed in the first content item playlist; generate a seed content attribute sequence based on attributes of at least a first seed content item of the set of seed content items and the sequential order for the set of seed content items; generate a recommended content attribute sequence that is likely to follow the seed content attribute sequence, the recommended content attribute sequence determined from the seed content attribute sequence and a statistical language model based on an analysis of a set of reference content attribute sequences, wherein the set of reference content attribute sequences were generated from a set of user created content playlists; and select a set of recommended content items to be added to the first content item playlist and performed sequentially after the set of seed content items in a recommended sequential order, the set of recommended content item and the recommended sequential order selected based on content attributes of the set of recommended content items and the recommended content attribute sequence.
9. The system of claim 8 , wherein the instructions further cause the computer processor to: select a subset of a set of available content times yielding a set of candidate content items, wherein the first recommended content item is selected from the set of candidate content items.