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.

A033856 Numbers k such that j(k)*phi(k) = sigma(phi(k)), j(k) = A033831(k).

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%I A033856 #9 Jul 01 2019 11:40:48
%S A033856 14,58,175,244,833,1017,1348,8653,33263,33497,33611,34099,34151,34529,
%T A033856 34771,36281,36449,36743,37367,37373,38311,38695,38735,38915,39035,
%U A033856 39263,39295,39431,39995,41015,41635,42119,46209,46617,46731,47067,49911,50007,50871
%N A033856 Numbers k such that j(k)*phi(k) = sigma(phi(k)), j(k) = A033831(k).
%H A033856 Amiram Eldar, <a href="/A033856/b033856.txt">Table of n, a(n) for n = 1..406</a>
%t A033856 j[n_] := DivisorSum[n, 1&, # > 2 && n/# < #-1 &]; aQ[n_] := j[n]*(p = EulerPhi[ n]) == DivisorSigma[1, p]; Select[Range[10^4], aQ] (* _Amiram Eldar_, Jul 01 2019 *)
%Y A033856 Cf. A000010, A000203, A033831, A033855.
%K A033856 easy,nonn
%O A033856 1,1
%A A033856 _Naohiro Nomoto_
%E A033856 More terms from _Amiram Eldar_, Jul 01 2019