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 A179627 #14 Jul 22 2025 08:20:13 %S A179627 2,6,5,12,11,8,10,15,12,14,68,16,70,21,67,10,23,15,20,66,74,25,71,22, %T A179627 76,19,57,65,73,11,32,21,59,29,18,13,26,18,45,23,23,15,31,77,20,77,28, %U A179627 47,12,25,55,36,17,44,79,52,22,30,14,30,41,76,27,57,84,27,19,73,81,24,81 %N A179627 a(n) = length of Collatz sequence starting with n-th prime. %H A179627 Reinhard Zumkeller, <a href="/A179627/b179627.txt">Table of n, a(n) for n = 1..10000</a> %H A179627 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CollatzProblem.html">Collatz Problem</a> %H A179627 Wikipedia, <a href="http://en.wikipedia.org/wiki/Collatz_conjecture">Collatz conjecture</a> %H A179627 <a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or Collatz) problem</a> %F A179627 a(n) = A006666(A000040(n)) + 1. [_Reinhard Zumkeller_, Apr 03 2012] %e A179627 For n=4 the a(n)=12 because the fourth prime is 7 and if you start with 7, the 12th term of syracuse-sequence is 1. The syracuse-sequence starting with 7 has the dimension 12. %o A179627 (Haskell) %o A179627 a179627 = (+ 1) . a006666 . a000040 -- _Reinhard Zumkeller_, Apr 03 2012 %K A179627 nonn %O A179627 1,1 %A A179627 Roland Schroeder (florola(AT)gmx.de), Jul 21 2010 %E A179627 Offset fixed by _Reinhard Zumkeller_, Apr 03 2012