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 A117283 #11 Mar 23 2021 05:20:20 %S A117283 1,2,3,5,7,11,12,13,14,16,17,19,23,29,31,37,41,43,47,53,59,61,63,67, %T A117283 71,73,79,81,83,89,96,97,101,103,107,109,112,113,115,124,127,128,131, %U A117283 137,139,149,151,157,163,167,173,179,181,187,191,193,197,199,211,223,227 %N A117283 Numbers k for which the cototient k-phi(k) is a cube. %H A117283 Amiram Eldar, <a href="/A117283/b117283.txt">Table of n, a(n) for n = 1..10000</a> %e A117283 63 is in the sequence because 63-phi(63) = 27, which is a cube. %t A117283 Select[Range[230], IntegerQ[(# - EulerPhi[ # ])^(1/3)] &] (* _Stefan Steinerberger_, Apr 24 2006 *) %o A117283 (PARI) isok(k) = ispower(k-eulerphi(k), 3); \\ _Michel Marcus_, Mar 23 2021 %Y A117283 Cf. A000010, A000578, A051953. %Y A117283 Cf. A117284, A117285, A117286, A117287, A117288, A117289. %K A117283 nonn %O A117283 1,2 %A A117283 Luc Stevens (lms022(AT)yahoo.com), Apr 23 2006