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 A015851 #14 Sep 08 2019 17:37:49 %S A015851 1,2,3,4,6,7,9,11,14,15,18,20,34,36,38,39,52,63,70,84,85,97,100,111, %T A015851 116,130,146,150,153,162,174,180,182,196,207,216,220,222,231,247,372, %U A015851 427,429,468,490,505,507,608,612,700,702,741,742,748,775,855,861 %N A015851 Numbers k such that phi(k) | sigma(k + 8). %t A015851 Select[Range[1, 999], Divisible[DivisorSigma[1, 8 + #], EulerPhi[#]] &] (* _David Nacin_, Mar 04 2012 *) %o A015851 (PARI) is(n)=!(sigma(n+8)%eulerphi(n)) \\ _Charles R Greathouse IV_, Sep 25 2012 %K A015851 nonn %O A015851 1,2 %A A015851 _Robert G. Wilson v_