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 A225173 #11 Feb 14 2018 03:20:13 %S A225173 1,1,2,4,9,21,38,82,164,261,424,749,1097,1721,2592,4351,7319,10725, %T A225173 17013,27773,44767,73914,118990,185059,275055,401059,617679,935331, %U A225173 1379826,2089569,2962015,3899417,5202824 %N A225173 Number of numbers which require n iterations of the unitary totient function (A047994) to reach 1. %H A225173 M. Lal, <a href="http://dx.doi.org/10.1090/S0025-5718-1974-0335419-3">Iterates of the unitary totient function</a>, Math. Comp., 28 (1974), 301-302. %Y A225173 Cf. A047994, A003271, A225172. %K A225173 nonn,more %O A225173 0,3 %A A225173 _N. J. A. Sloane_, May 01 2013 %E A225173 a(16)-a(32) from _Donovan Johnson_, May 02 2013