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 A015845 #18 Sep 09 2019 01:20:39 %S A015845 1,2,3,4,5,6,7,8,12,16,20,22,24,26,27,28,31,35,39,40,50,58,63,70,88, %T A015845 95,108,112,116,120,135,152,163,183,224,228,241,273,315,323,364,369, %U A015845 455,476,520,524,616,620,632,703,782,855,903,945,950,1008,1124,1188 %N A015845 Numbers k such that phi(k) | sigma(k + 7). %H A015845 Ivan Neretin, <a href="/A015845/b015845.txt">Table of n, a(n) for n = 1..1000</a> %t A015845 Select[Range[3000], Divisible[DivisorSigma[1, 7 + #], EulerPhi[#]] &] (* _David Nacin_, Mar 03 2012 *) %o A015845 (PARI) is(n)=!(sigma(n+7)%eulerphi(n)) \\ _Charles R Greathouse IV_, Sep 25 2012 %K A015845 nonn %O A015845 1,2 %A A015845 _Robert G. Wilson v_ %E A015845 a(1) = 1 inserted by _Ivan Neretin_, Feb 05 2017