cp's OEIS Frontend

A226117 Numbers n such that phi(sigma(tau(n))) = tau(sigma(phi(n))).

%I A226117 #8 Dec 12 2021 10:56:41
%S A226117 1,3,4,5,14,17,20,21,22,26,51,63,65,66,72,76,80,84,90,100,106,112,132,
%T A226117 135,150,152,165,182,190,196,221,222,232,246,255,290,291,292,294,320,
%U A226117 326,375,386,396,424,450,460,489,530,561,567,585,588,600,606,608,615
%N A226117 Numbers n such that phi(sigma(tau(n))) = tau(sigma(phi(n))).
%H A226117 Paolo P. Lava, <a href="/A226117/b226117.txt">Table of n, a(n) for n = 1..1000</a>
%e A226117 For n=23529 we have:
%e A226117 phi(23529)=13200 -> sigma(13200)=46128 -> tau(46128)=30.
%e A226117 tau(23529)=16 -> sigma(16)=31 -> phi(31)=30.
%p A226117 with(numtheory); A226117:=proc(q) local n;
%p A226117 for n from 1 to q do
%p A226117 if phi(sigma(tau(n)))=tau(sigma(phi(n))) then print(n);
%p A226117 fi; od; end: A226117(10^6);
%t A226117 Select[Range[700],EulerPhi[DivisorSigma[1,DivisorSigma[0,#]]] == DivisorSigma[ 0,DivisorSigma[ 1,EulerPhi[ #]]]&] (* _Harvey P. Dale_, Dec 12 2021 *)
%Y A226117 Cf. A000005, A000010, A000203, A033632, A067160, A076361, A226118, A226119.
%K A226117 nonn
%O A226117 1,2
%A A226117 _Paolo P. Lava_, May 27 2013