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 A164647 #7 Jul 14 2012 11:32:31 %S A164647 1463,2945,8255,70091,81809,89999,122759,187625,193039,196469,388585, %T A164647 494665,671365,2311673,2442583,2687113,4209985,4705285,4902247, %U A164647 5393017,5667389,5866003,9248323,10795967,11345411,11670275,11773027,13290485,13741273,15978487 %N A164647 Numbers n such that sigma(n)/phi(n) = 16/9. %C A164647 A subsequence of A011257. %H A164647 Donovan Johnson, <a href="/A164647/b164647.txt">Table of n, a(n) for n = 1..1000</a> %o A164647 (PARI) for( n=1,10^7, sigma(n)==16/9*eulerphi(n) && print1(n",")) %Y A164647 Cf. A000010 (=phi), A000203 (=sigma), A068390, A163667, A164646. %K A164647 nonn %O A164647 1,1 %A A164647 _M. F. Hasler_, Aug 22 2009 %E A164647 More terms from _Farideh Firoozbakht_, Sep 22 2009