|
%I #19 Jun 17 2018 01:59:24
%S 7,209,10013,11687,12857,17537,27577,28067,700321,770431,1321189,
%T 1542281,1681861,1963039,2282641,2313961,2664259,3308041,3709057,
%U 3859207,3929761,4315751,4380541,4561381,5193001,5331001,5576519,5962333,6561511,7332919,10065991,12133627,13678613,14313949,15263831
%N Numbers k such that 4*phi(k) = 3*sigma(k).
%H Jud McCranie, <a href="/A065819/b065819.txt">Table of n, a(n) for n = 1..10000</a> (first 65 terms from Harry J. Smith)
%e For m=10013, phi(m)=8640, sigma(m)=11520, 34560 = 4*phi = 3*sigma.
%t Do[s = 4*EulerPhi[n]-3*DivisorSigma[1, n]; If[Equal[s, 0], Print[n]], {n, 1, 10000000}]
%o (PARI) { n=0; for (m=1, 10^9, if (4*eulerphi(m) == 3*sigma(m), write("b065819.txt", n++, " ", m); if (n==65, return)) ) } \\ _Harry J. Smith_, Oct 31 2009
%Y Cf. A000010, A000203, A062699.
%K nonn
%O 1,1
%A _Labos Elemer_, Nov 23 2001
|
