Hello MathFun, This (partially) self-describing sequence says, for every a(n): the a(n)th *digit* of the sequence is a "1": 1,3,10,20,22,31,32,33,34,35,41,51,52,53,54,55,111,112,200,210,220, 222,231,1111... So the 1st digit of the sequence is indeed a "1", and the 3rd, and the 10th, and the 20st, and the 22nd, etc. ^^ This column is the sequence itself (which will replace A098645 in the OEIS when Neil will be back from Europe). Many such "self-1-describing" sequences can be build, for ins- tance this one (all "1"s must be described, not a few of them): 1,4,5,11,20,22,31,... Question: Find the *finite* such "self-1-describing" sequence where 16 "1"s can be seen and where the last term is the smallest one. Best, É. (I'll send a bunch of "self-n-describing" such seq to the OEIS this week or so; BTW I will change also A098670 because the concept of "slowest growingness" is ambiguous -- actually quite impossible to define for such seq.)