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 A049116 #9 Jul 19 2019 14:24:11
%S A049116 1,2,2,4,4,2,2,8,2,4,4,4,4,2,8,16,16,2,2,8,4,4,4,8,8,4,2,4,4,8,8,32,8,
%T A049116 16,8,4,4,2,8,16,16,4,4,8,8,4,4,16,4,8,32,8,8,2,16,8,4,4,4,16,16,8,4,
%U A049116 64,16,8,8,32,8,8,8,8,8,4,16,4,16,8,8,32,2,16,16,8,64,4,8,16,16,8,8,8
%N A049116 Repeatedly apply Euler phi to n; a(n) = highest power of 2 that is seen.
%H A049116 Amiram Eldar, <a href="/A049116/b049116.txt">Table of n, a(n) for n = 1..10000</a>
%e A049116 If n is a power of 2, then it is of largest exponent. If n=2400, then its phi-sequence is {2400,640,256,128,64,32,16,8,4,2,1}. The value of first power of 2 is 256. Thus a(2400)=256.
%t A049116 Table[SelectFirst[NestWhileList[EulerPhi[#]&,n,#>1&],IntegerQ[Log[2,#]]&],{n,120}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 23 2019 *)
%Y A049116 Cf. A000010.
%K A049116 nonn
%O A049116 1,2
%A A049116 _Labos Elemer_