I may not "take him seriously", but I DO know who he is, while noting writing twenty books or so happens to be an accomplishment NO MATTER who one is or isn't.
There's a guy in Brazil who's written several hundreds of books. He is known for being able to churn out an entire, rather thick, novel overnight. The novels are completely formula, devoid of any real literary value, yet he can meet your requirement in less than a month.
BTW, Isaac Asimov wrote over 400 novels, serious and fluff fiction and serious nonfiction (his works on the Bible and Shakespeare are quite insightful and show serious research and study), and yet that doesn't make the fundies here respect him any more because of his atheism.