This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A216813 #31 Aug 11 2014 22:45:49 %S A216813 0,3,6,18,39,96,201,582,1220,2590,5345,10919,21859,44167,88629,178050, %T A216813 356598,715084,1431514,2866876,5736311,11480839,22966942,45949687, %U A216813 91910241,183852468,367726473,735517466,1471078571,2942286009,5884661772,11769583511,23539346216,47079214312,94158788295 %N A216813 Sum of tail length of S over all 2^n strings S consisting of n 2's and 3's. %C A216813 "Tail length" is defined in A216730. %H A216813 Benjamin Chaffin and N. J. A. Sloane, <a href="/A216813/b216813.txt">Table of n, a(n) for n = 1..40</a> %H A216813 B. Chaffin, J. P. Linderman, N. J. A. Sloane and Allan Wilks, <a href="http://arxiv.org/abs/1212.6102">On Curling Numbers of Integer Sequences</a>, arXiv:1212.6102, Dec 25 2012. %H A216813 B. Chaffin, J. P. Linderman, N. J. A. Sloane and Allan Wilks, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL16/Sloane/sloane3.html">On Curling Numbers of Integer Sequences</a>, Journal of Integer Sequences, Vol. 16 (2013), Article 13.4.3. %H A216813 <a href="/index/Cu#curling_numbers">Index entries for sequences related to curling numbers</a> %F A216813 a(n) = A094005(n) - n*2^n. %F A216813 Up to n=32, the average tail length a(n)/2^n seems to be approaching a number around 2.74. %Y A216813 Cf. A094005, A216730. %K A216813 nonn %O A216813 1,2 %A A216813 _N. J. A. Sloane_, Sep 18 2012 - Sep 21 2012, Oct 23 2012