# A question about a number series/sequence. **URL:** \ **Category:** Factual Questions\ **Created:** [November 17, 2002, 6:02pm UTC](https://boards.straightdope.com/t/a-question-about-a-number-series-sequence/137182 "2002-11-17T18:02:18Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Drew\_Blade](https://avatars.discourse-cdn.com/v4/letter/d/958977/32.png) [@Drew\_Blade](https://boards.straightdope.com/u/Drew_Blade)\ **Post date:** [November 17, 2002, 6:02pm UTC](https://boards.straightdope.com/t/a-question-about-a-number-series-sequence/137182/1 "2002-11-17T18:02:18Z")
If you continue generating the numbers to this list, do numerals greater than 3 ever appear? If so, how far do you have to go for a 4 to appear? And a 5 and 6, and so on? (I am purposely not explaining how to generate the next number in the list because if you DON’T know how to make the next entry, I don’t want to take away the joy of discovering it.) 1 11 21 1211 111221 312211 13112221 . . . . ---
**Author:** ![Jabba](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@Jabba](https://boards.straightdope.com/u/Jabba)\ **Post date:** [November 17, 2002, 6:13pm UTC](https://boards.straightdope.com/t/a-question-about-a-number-series-sequence/137182/2 "2002-11-17T18:13:22Z")
No. As you know ( if you know how the sequence is generated) the numbers are formed in pairs. Suppose the number 4 appears somewhere and consider the first row in which it appears. The the previous row must have had four consecutive identical digits, say NNNN. Ther are two possibilities: (i) xN NN Ny This is impossible; since the xN and NN would actually have been combined into (x+N)N (ii)NN NN This is impossible for the same reason. ---
**Author:** ![Drew\_Blade](https://avatars.discourse-cdn.com/v4/letter/d/958977/32.png) [@Drew\_Blade](https://boards.straightdope.com/u/Drew_Blade)\ **Post date:** [November 17, 2002, 7:25pm UTC](https://boards.straightdope.com/t/a-question-about-a-number-series-sequence/137182/3 "2002-11-17T19:25:42Z")
Thanks Jabba.