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 A015796 #27 Sep 10 2019 08:49:30 %S A015796 4,10,32,60,88,688,2544,3424,12200,62848,777984,1037824,16734208, %T A015796 67022848,8625555968,51537444864,1099500617728 %N A015796 Numbers k such that phi(k) + 5 | sigma(k). %C A015796 a(18) <= 17592142004224. In general, if 2^k-11 is prime (A096817) then 2^(k-2)*3*(2^k-11) is a term for k > 3. Moreover, if 2^k-21 is prime (A096820) then 2^(k-2)*(2^k-21) is a term for k > 4. - _Giovanni Resta_, Sep 09 2019 %t A015796 Select[Range[100000], %t A015796 Divisible[DivisorSigma[1, #], EulerPhi[#] + 5] &] (* _David Nacin_, Feb 28 2012 *) %Y A015796 Cf. A000010, A000203, A056097, A015812, A015792, A015793, A015797, A015798, A015799, A015800, A015801, A015804, A015805, A096817, A096820. %K A015796 nonn,more %O A015796 1,1 %A A015796 _Robert G. Wilson v_ %E A015796 More terms from _Jud McCranie_, Dec 26 1999 %E A015796 Offset corrected and a(15)-a(16) from _Donovan Johnson_, Feb 28 2012 %E A015796 a(17) from _Giovanni Resta_, Sep 09 2019