Katy Perry at Nokia Theatre L.A. Live

MUSIC

To judge Katy Perry as inauthentic or unoriginal would be wrong; as with a great ad campaign, familiarity is her greatest achievement. She can feign a rocker’s stance on the Alanis-inspired “Circle the Drain” or a hip-hop diva’s stutter on the Rihanna-influenced “E.T.” and convince you it fits her perfectly. Nokia Theatre, 777 Chick Hearn Court, L.A. 8 p.m. Fri-Sun. $34.50-$49.50. nokiatheatrelalive.com.