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 A092589 #16 Jun 09 2024 09:04:48
%S A092589 0,1,3,1,15,5,63,1,177,89,913,-319,4095,2393,10617,1,65535,8897,
%T A092589 262143,-44287,729537,543553,4015777,-1753087,15622785,11162969,
%U A092589 46358529,-1452031,265390977,-2270911,1073741823,1,2668569153,2862962009,15344762817,-8238350335,68103158337,45811586393
%N A092589 a(n) = -A065395(2^n).
%H A092589 Amiram Eldar, <a href="/A092589/b092589.txt">Table of n, a(n) for n = 0..1205</a>
%F A092589 a(n) = phi(2^(n+1)-1) - 2^n + 1 = A053287(n+1) - A000225(n). - _Amiram Eldar_, Jun 09 2024
%t A092589 fs[x_] := EulerPhi[DivisorSigma[1, x]]; sf[x_] := DivisorSigma[1, EulerPhi[x]]; Table[fs[2^w]-sf[2^w], {w, 0, 65}]
%Y A092589 Cf. A000010, A000203, A000225, A033632, A053287, A065395, A092584, A092585, A092586, A092587, A092588.
%K A092589 sign
%O A092589 0,3
%A A092589 _Labos Elemer_, Mar 02 2004
%E A092589 Offset changed to 0, a(0) prepended and name corrected by _Amiram Eldar_, Jun 09 2024