cp's OEIS Frontend

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.

A015797 Numbers n such that phi(n) + 6 | sigma(n).

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%I A015797 #27 Jul 15 2017 11:23:47
%S A015797 14,20,54,56,234,286,456,686,735,980,1176,1224,1470,2000,3296,21645,
%T A015797 34632,37496,43290,46620,62336,191616,277808,779568,1124528,4095712,
%U A015797 16726016,17409376,50251776,149911936,177383296,12883623936,42932880896,295964664896
%N A015797 Numbers n such that phi(n) + 6 | sigma(n).
%C A015797 a(35) > 10^12. - _Donovan Johnson_, Feb 28 2012
%e A015797 phi(14)+6 = 12, which divides sigma(14)=24, so 14 is in the sequence.
%t A015797 Select[Range[100000],
%t A015797 Divisible[DivisorSigma[1, #], EulerPhi[#] + 6] &] (* _David Nacin_, Feb 28 2012 *)
%o A015797 (PARI) isok(n) = (sigma(n) % (eulerphi(n) + 6)) == 0; \\ _Michel Marcus_, Jul 15 2017
%Y A015797 Cf. A000010, A000203.
%K A015797 nonn
%O A015797 1,1
%A A015797 _Robert G. Wilson v_
%E A015797 More terms from _Jud McCranie_, Dec 25 1999
%E A015797 a(32)-a(34) from _Donovan Johnson_, Feb 28 2012