|
%I #7 Apr 15 2017 09:04:29
%S 1,14,61,966,1428,9174,15642,19934,22155,27075,36650,48731,51095,
%T 54184,57902,59711,61039,89276,98645,113080,126850,140283,142149,
%U 154670,165822,190908,197705,198712,202096,203107,247268,274368,274716,307836,311925,331037,366740
%N Numbers n such that sigma(Rev(phi(n))) = phi(Rev(sigma(n))), where sigma is the sum of divisors and phi the Euler totient function.
%H Paolo P. Lava, <a href="/A252255/b252255.txt">Table of n, a(n) for n = 1..100</a>
%e phi(14) = 6, Rev(6) = 6 and sigma(6) = 12;
%e sigma(14) = 24, Rev(24) = 42 and sigma(42) = 12.
%p with(numtheory): T:=proc(w) local x, y, z; x:=0; y:=w;
%p for z from 1 to ilog10(w)+1 do x:=10*x+(y mod 10); y:=trunc(y/10); od; x; end:
%p P:=proc(q) local a, b, k; global n; for n from 1 to q do
%p if sigma(T(phi(n)))=phi(T(sigma(n))) then print(n); fi; od; end: P(10^12);
%t Select[Range[400000],DivisorSigma[1,IntegerReverse[EulerPhi[#]]] == EulerPhi[ IntegerReverse[ DivisorSigma[ 1,#]]]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 15 2017 *)
%Y Cf. A000010, A000203, A069225, A070835, A070856.
%K nonn,base
%O 1,2
%A _Paolo P. Lava_, Dec 16 2014
|
