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 A053046 #18 Aug 17 2024 09:01:35
%S A053046 0,0,1,1,1,2,3,3,5,5,5,6,7,8,9,9,9,11,13,13,15,15,15,16,16,17,20,21,
%T A053046 22,23,24,24,25,25,26,28,30,32,34,34,34,36,38,38,40,40,40,41,43,43,44,
%U A053046 45,46,49,49,50,53,54,55,56,57,58,61,61,62,63,64,64,65,66,67,69,71,73,74
%N A053046 a(n) is the number of terms that are not powers of 2 among the iterates of the Euler phi function when it is iterated with initial value n!.
%C A053046 Non-powers of 2 arise at the beginning of iteration chains without interruption. Analogous to A053036.
%H A053046 Amiram Eldar, <a href="/A053046/b053046.txt">Table of n, a(n) for n = 1..10000</a>
%F A053046 a(n) = 1 + A053044(n) - A053045(n). - _R. J. Mathar_, Jan 09 2017
%e A053046 For n = 10, the initial value is 10! = 3628800 and the iteration chain is {3628800, 829440, 221184, 73728, 24576, 8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1}. Its length is 19 and there are 5 values that are not powers of 2: 10!, ..., 24576. Thus a(10) = 5.
%Y A053046 Cf. A000010, A000142, A048855, A053036, A053044, A053045.
%K A053046 nonn
%O A053046 1,6
%A A053046 _Labos Elemer_, Feb 25 2000