%I #16 May 22 2024 10:20:44

%S 1,2,6,12,840,332640

%N Numbers k such that phi(k) divides sigma(k) and sigma(k)/k > sigma(m)/m for all m < k.

%C a(7) > A004394(10^5) > 10^12146, if it exists. - _Amiram Eldar_, May 21 2024

%o (PARI) lista(kmax) = {my(f, r, rm = 0); for(k = 1, kmax, f = factor(k); r = sigma(f, -1); if(r > rm, rm = r; if(!(sigma(f) % eulerphi(f)), print1(k, ", "))));} \\ _Amiram Eldar_, May 21 2024

%Y Intersection of A020492 and A004394.

%K nonn

%O 1,2

%A _Walter Nissen_