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 A090557 #22 May 02 2016 07:45:18 %S A090557 1,1,2,2,4,4,4,4,12,12,12,12,24,24,24,24,24,48,96,96,96,192,192,192, %T A090557 192,192,192,192,192,192,192,384,384,384,384,384,768,768,768,768,768, %U A090557 768,768,1536,1536,1536,1536,1536,1536,1536,1536,3072,3072,3072,3072,3072 %N A090557 a(n) = phi(A090556(n)). %C A090557 Starting at n=9, all known terms are of the form 3*2^k. - _Ivan Neretin_, May 01 2016 %H A090557 Ivan Neretin, <a href="/A090557/b090557.txt">Table of n, a(n) for n = 1..308</a> %t A090557 EulerPhi@ NestList[Function[n, SelectFirst[Range[n + 1, 10^4], Divisible[EulerPhi@ #, EulerPhi@ n] &]], 1, 55] (* _Michael De Vlieger_, May 01 2016, Version 10 *) %Y A090557 Cf. A014573, A090556. %K A090557 nonn %O A090557 1,3 %A A090557 _Amarnath Murthy_, Dec 10 2003 %E A090557 More terms from _David Wasserman_, Jan 04 2006 %E A090557 Missing term a(1) prepended by _Ivan Neretin_, May 01 2016