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 A133426 #9 Jul 10 2015 19:59:07 %S A133426 8,50,162,470,9584,28400,91890,193040,265070,291824,337100,388830, %T A133426 524070,3231824,18052070,30949850,31021880,65552768,774659600, %U A133426 10276607888,38128783428,190067750300,4835458627140,25515567812750 %N A133426 Analog of A060410 for the 7x+1 problem (cf. A133421). %C A133426 The 7x+1 map sends x to x/2 if x is even, x/3 if x is divisible by 3, x/5 if x is divisible by 5, otherwise 7x+1. %H A133426 N. J. A. Sloane, <a href="/A133426/b133426.txt">Table of n, a(n) for n=1..53</a> (from the web page of Tomás Oliveira e Silva) %H A133426 Tomás Oliveira e Silva, <a href="http://sweet.ua.pt/tos/3x+1.html">The px+1 problem</a> %H A133426 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a> %Y A133426 Cf. A133421, A133425, A133419, ... %K A133426 nonn %O A133426 1,1 %A A133426 _N. J. A. Sloane_, Nov 27 2007