In 1948 he provided a long-awaited elementary proof of the prime number theorem, around the same time that [[Paul Erdős]] gave an independent proof. He immigrated to the United States and works at the Institute for Advanced Study in [[Princeton University|Princeton]] where he died in 2007. | In 1948 he provided a long-awaited elementary proof of the prime number theorem, around the same time that [[Paul Erdős]] gave an independent proof. He immigrated to the United States and works at the Institute for Advanced Study in [[Princeton University|Princeton]] where he died in 2007. |