LOST AND FOUND:Dan Brown's ''Lost Symbol'' enters the hardcover fiction list at No. 1, as predicted in the Dead Sea Scrolls, the Federalist Papers and Season 4 of ''The X-Files.'' Can we all stop talking about him now? O.K., maybe not. One of the more titillating biographical details being bandied about in the coverage of the new release is that Brown (inset) was once in an undergraduate writing workshop at Amherst with David Foster Wallace -- who apparently failed to get him to take up footnotes. But it turns out that he was also in the same fraternity (Psi Upsilon) as another future best-selling author, Harlan Coben. After Brown, then a middling thriller writer, showed him the manuscript of ''The Da Vinci Code,'' Coben promised to help promote it, only to have the ''Da Vinci'' juggernaut block his own subsequent progress up the best-seller list. ''I called up Dan and told him I was no longer helping to promote his book,'' Coben joked to Amherst magazine. Not that it mattered: ''The Da Vinci Code'' spent 166 weeks on the hardcover list. [ABSTRACT FROM PUBLISHER]