Brown twittered "HAPPY BIRTHDAY ROBYN" to Rihanna

　　Brown also twittered "HAPPY BIRTHDAY ROBYN" to Rihanna, who turned 24 on Monday. A representative for Rihanna said she had no comment. An email seeking comment from Brown's representatives went unreturned Monday.

　　Chris Brown and Rihanna are back together, musically speaking.Two songs featuring the singers hit the Internet on Monday. Brown sings on the remix of Rihanna's sexually charged song "Birthday Cake," and she's on the remix of his upbeat tune "Turn up the Music."

　　Brown tweeted a link to the new version of "Turn up the Music" on Monday, and Rihanna later retreated it. She also tweeted about the remix for "Birthday Cake."

　　Rihanna, whose full name is Robyn Rihanna Fenty, told Esquire magazine in its October 2010 issue that she no longer resented Brown and that she enjoys his music.The two singers first collaborated musically in 2007 on the remix to her monster hit "Umbrella."

　　Information come from online news.Thank you for your reading.