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 A077092 #22 May 09 2025 00:06:04
%S A077092 0,4,24,8064,34944,35520,38880,69480,268560,420096,1054944,2946560,
%T A077092 3054080,5660160,6621120,9768960,10264320,25885760,29062656,33933312,
%U A077092 36484992,38707200,78532608,163418112,260601600,458987520,4044349440
%N A077092 Fixed points of iteration in A077091.
%C A077092 When iteration of f(k) = phi(sigma(k)-phi(k)) is started at various initial values, not ending in cycles and converging, it ends at these fixed points.
%C A077092 a(28) <= 11435212800. a(29) <= 15083274240. a(30) <= 90215424000. - _Donovan Johnson_, Dec 14 2009
%e A077092 n=30: FixedPointList={30,32,46,20,16,22,12,8,10,6,4},end=4; n=94: FixedPointList={94,42,24},end=24. n=41708: FixedPointList={41708,26064,32352,21216,15232,8064},end=8064; n=12100: FixedPointList={12100,24000,34944},end=34944.
%t A077092 f[x_] := EulerPhi[DivisorSigma[1, x]-EulerPhi[x]] Do[s=NestList[f, n, 100]; s1=Part[s, 99]; s2=Part[s, 100]; If[Equal[s1, s2]&&!PrimeQ[n], Print[{n, s1}]], {n, 1, 1000}]
%Y A077092 Cf. A077090, A077091, A077093, A077094, A077095, A077096, A077099, A077100.
%K A077092 nonn
%O A077092 1,2
%A A077092 _Labos Elemer_, Oct 31 2002
%E A077092 a(9) corrected and a(11)-a(27) from _Donovan Johnson_, Dec 14 2009