Hello SeqFans, if all a(n)s must be prime, using the method here: http://www.research.att.com/~njas/sequences/A001462 ... then we'll get S: S = 2,2,3,3,5,5,5,7,7,7,11,11,11,11,11,13,13,13,13,13,17,17,17,17,17,... chunks: 2 2 3 3 5 5 5 Best, É. (same can be done with composites, triangulars, squares, Fibonaccis, etc.)