A British teenager has been sentenced to at least 16 1/2 years in prison for plotting a bombing whose potential targets included an Elton John concert on the 15th anniversary of the September 11 attacks.<br/>'<br/>Judge Michael Topolski said 19-year-old Syed had been intent on carrying out an act of mass murder in this country. He sentenced him to life with no chance of parole for 16 1/2 years. Haroon Syed had admitted planning terrorist acts at an earlier court hearing.<br/><br/>Prosecutors said Syed tried to buy weapons and explosives online from an extremist named "Abu Yusuf," who was actually a series of British intelligence agents.<br/>