NEW YORK (AP) — The critics savaged Jay Leno’s prime-time experiment. Viewers gave it the biggest audience for an entertainment show since the “American Idol” finale in May. An estimated 18.4 million viewers sampled the first night of “The Jay Leno Show” Monday, Nielsen Media Research said. But the most hyped debut of the fall season had the added advantage of being piggybacked onto one of the country’s biggest stories. Leno interviewed Kanye West about why he had interrupted Taylor Swift the night before on the MTV Video Music Awards.