A068567 - OEIS

%I #6 Apr 11 2020 08:02:41

%S 12,24,30,40,45,48,56,60,63,70,80,84,90,96,105,112,120,126,132,135,

%T 140,154,160,165,168,175,176,180,182,189,192,195,198,208,210,220,224,

%U 231,234,240,252,260,264,270,273,275,280,286

%N Numbers k such that gpf(k) < k/gpf(k) and gpf(k/gpf(k)) < gpf(k), where gpf(n) is the greatest prime factor of n, A006530.

%H Hugo Pfoertner, <a href="/A068567/b068567.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI) gpf(j)={if(j==1, 1, my(f=factor(j)); f[#f[, 2], 1])};

%o for(k=1,300,my(L=gpf(k));if(L<k/L,if(gpf(k/L)<L,print1(k,", ")))) \\ _Hugo Pfoertner_, Apr 11 2020

%Y Cf. A063539.

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Mar 25 2002