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 A280929 #11 Jan 11 2017 07:48:49 %S A280929 2,3,2,1,4,1,2,2,3,1,2,2,4,1,2,3,3,4,2,2,6,1,4,3,3,1,2,2,4,3,2,4,6,1, %T A280929 2,5,5,1,2,3,3,7,8,2,4,1,2,4,3,4,6,2,6,3,2,3,3,1,2,4,4,1,17,5,6,7,2,2, %U A280929 5,3,2,6,5,1,2,2,4,3,4,4,3,1,6,8,8,1,2,3,3,5,2,2,6,1,15,5,3,4,2,5 %N A280929 Number of steps required to reach the first prime when starting from n in the Collatz (or '3x+1') problem. %C A280929 If n=p*2^k, where k>0 and p is some prime then a(n)=k. %C A280929 If n is odd then a(n)=a(3n+1)+1. %C A280929 If n is even then a(n)=1 or a(n)=a(n/2)+1. %C A280929 If n is composite then a(n)=A274472(n). %H A280929 Dmitry Kamenetsky, <a href="/A280929/b280929.txt">Table of n, a(n) for n = 1..10000</a> %e A280929 The Collatz iteration for 33 is 100, 50, 25, 76, 38, 19, 58, 29, ... 1. The first prime (19) is reached after 6 steps, so a(33)=6. %Y A280929 Cf. A006577, A274472. %K A280929 nonn %O A280929 1,1 %A A280929 _Dmitry Kamenetsky_, Jan 11 2017