franktaw at netscape.net wrote: > Another curiosity: in the first 1000 terms, after 3, 198, 270, 570, > 522, 600, 822, and 882, we have a(n+1) = a(n)^2-1. I'll venture that, after the 3, these numbers are all going to be members of A014574 (average of twin prime pairs).