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 A078550 #14 Apr 11 2024 04:10:09
%S A078550 38,46,54,87,95,114,126,134,135,138,147,161,174,182,184,209,215,216,
%T A078550 222,230,258,285,294,297,299,315,322,398,402,414,430,437,455,456,483,
%U A078550 540,546,551,552,598,609,623,627,632,635,644,645,670,690,762,783,805
%N A078550 Non-balanced numbers in A015774.
%H A078550 Amiram Eldar, <a href="/A078550/b078550.txt">Table of n, a(n) for n = 1..10000</a>
%F A078550 sigma_15(a(n)) mod phi(a(n)) = 0; sigma(a(n)) mod phi(a(n)) <> 0.
%t A078550 q[n_] := Sign[Mod[DivisorSigma[{1, 15}, n], EulerPhi[n]]] == {1, 0}; Select[Range[1000], q] (* _Amiram Eldar_, Apr 11 2024 *)
%o A078550 (PARI) is(n) = {my(f = factor(n), phi = eulerphi(f)); (sigma(f) % phi) && !(sigma(f, 15) % phi);} \\ _Amiram Eldar_, Apr 11 2024
%Y A078550 Cf. A000010, A000203, A013963, A015774, A020492, A078539.
%Y A078550 Cf. A074866, A074868, A077801, A077803, A078544, A078549.
%K A078550 nonn
%O A078550 1,1
%A A078550 _Labos Elemer_, Dec 05 2002
%E A078550 Name corrected by _Amiram Eldar_, Apr 11 2024