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 A066418 #21 Jan 12 2020 11:31:11 %S A066418 2,3,4,5,6,7,8,12,15,27,30,40,44,57,117,128,171,236,399,408,510,1623, %T A066418 3597,3915,4616,4684,7335,10197,10768,14144,32768,39387,76035,77097, %U A066418 106605,162450,196080,219966,391696 %N A066418 Numbers k for which phi(k) + anti-phi(k) = k. %C A066418 Anti-phi(n) (A066452) is the number of numbers coprime to all the anti-divisors of n. %C A066418 See A066272 for definition of anti-divisor. %H A066418 Jon Perry, <a href="https://web.archive.org/web/20060923020029/http://www.users.globalnet.co.uk/~perry/maths/antidivisorother2.htm">Anti-phi function</a> [Wayback Machine link] %H A066418 Jon Perry, <a href="/A066272/a066272a.html">The Anti-divisor</a> [Cached copy] %H A066418 Jon Perry, <a href="/A066272/a066272.html">The Anti-divisor: Even More Anti-Divisors</a> [Cached copy] %e A066418 The anti-divisors of 7 are 1, 2, 3 and 5. Therefore of the integer 1-6, only 1 is coprime to 2, 3 and 5, therefore anti-phi(7)=1. phi(7)=6, therefore anti-phi(7)+phi(7)=7 %Y A066418 Cf. A066416, A066417, A058838, A066241, A066272, A066452. %K A066418 nonn,more %O A066418 1,1 %A A066418 _Jon Perry_, Dec 28 2001 %E A066418 a(21)-a(34) from _Nathaniel Johnston_, Apr 20 2011 %E A066418 a(35)-a(39) from _Amiram Eldar_, Jan 12 2020