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.

A114072 Numbers k such that phi(k) + k is a fourth power.

This page as a plain text file.
%I A114072 #16 Jan 18 2024 01:39:26
%S A114072 12,41,172,176,192,313,385,972,1008,1201,2732,2752,2816,3072,6668,
%T A114072 7321,14281,15552,16128,25616,29425,41761,43696,43712,44032,45056,
%U A114072 49152,78732,78768,79056,81648,84240,97241,106688,123921,139921
%N A114072 Numbers k such that phi(k) + k is a fourth power.
%H A114072 Amiram Eldar, <a href="/A114072/b114072.txt">Table of n, a(n) for n = 1..500</a>
%e A114072 phi(41) + 41 = 81 = 3^4.
%t A114072 Select[Range[140000],IntegerQ[Surd[#+EulerPhi[#],4]]&] (* _Harvey P. Dale_, Sep 27 2020 *)
%o A114072 (PARI) isok(n) = ispower(eulerphi(n) + n, 4); \\ _Michel Marcus_, Jan 09 2014
%Y A114072 Cf. A000010, A121048, subsequence of A114073.
%K A114072 nonn
%O A114072 1,1
%A A114072 _Giovanni Resta_, Feb 13 2006