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 A112420 #17 Feb 09 2017 11:49:14 %S A112420 1,3,1,8,2,1,3,1,5,2,1,4,2,6,3,1,4,2,7,3,1,5,1,8,4,1,6,1,9,2,1,4,2,6, %T A112420 3,9,4,1,6,3,1,5,1,7,2,1,3,1,5,2,7,3,1,5,1,8,4,1,6,1,9,2,1,7,3,1,9,4, %U A112420 2,6,3,1,5,2,1,3,1,5,2,8,4,1,6,1,9,2,1,4,2,6,3,1,8,2,1,3,1,5,2,1,4,2,6,3,1 %N A112420 Leading digits in 3x+1 chain starting with the number 1117065. %C A112420 The 3x+1 chain starts 1117065 -> 3351196 -> 1675598 -> 837799 and enters a 4->2->1->4->.. cycle after 527 iterations. The current sequence shows the most significant decimal digit after each iteration. [_R. J. Mathar_, Jul 26 2010] %H A112420 Michel Marcus, <a href="/A112420/b112420.txt">Table of n, a(n) for n = 1..600</a> %H A112420 A. V. Kontorovich & S. J. Miller, <a href="https://arxiv.org/abs/math/0412003">Benford's Law, Values Of L-Functions And The 3x+1 Problem</a>, arXiv:math/0412003 [math.NT], 2004-2005. %H A112420 J. C. Lagarias and K. Soundararajan, <a href="https://arxiv.org/abs/math/0509175">Benford's Law for the 3x+1 Function</a>, arXiv:math/0509175 [math.NT], 2005-2006. %H A112420 P. Picart, <a href="http://trucsmaths.free.fr/js_syracuse.htm">Algorithme de Collatz et conjecture de Syracuse</a> %H A112420 <a href="/index/Be#Benford">Index entries for sequences related to Benford's law</a> %o A112420 (PARI) lista(nn) = my(c = 1117065); for (n=1, nn, print1(digits(c)[1], ", "); if (c % 2, c = 3*c+1, c = c/2);); \\ _Michel Marcus_, Nov 05 2016 %Y A112420 Cf. A033958. %K A112420 nonn,base %O A112420 1,2 %A A112420 _Lekraj Beedassy_, Dec 10 2005 %E A112420 a(103) corrected by _Michel Marcus_, Nov 05 2016