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 A067878 #17 Apr 25 2025 05:27:18
%S A067878 1,10,33,46,65,77,123,136,221,371,385,423,513,532,545,572,660,702,753,
%T A067878 1248,1566,1643,1720,2033,2635,3243,4533,4798,5177,5346,5495,5605,
%U A067878 6460,7463,7565,7683,7739,8201,9342,9741,10780,10792,11679,11880,12256
%N A067878 Numbers k such that sigma(k) = phi(k*omega(k)-1).
%H A067878 Amiram Eldar, <a href="/A067878/b067878.txt">Table of n, a(n) for n = 1..1000</a>
%t A067878 Select[Range[13000],DivisorSigma[1,#]==EulerPhi[#*PrimeNu[#]-1]&] (* _Harvey P. Dale_, Feb 02 2015 *)
%o A067878 (PARI) isok(k) = {my(f = factor(k)); sigma(f) == eulerphi(k * omega(f) - 1);} \\ _Amiram Eldar_, Apr 25 2025
%Y A067878 Cf. A000010 (phi), A000203 (sigma), A001221 (omega), A328260.
%K A067878 nonn
%O A067878 1,2
%A A067878 _Benoit Cloitre_, Mar 02 2002