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Numbers n such that sopfr(n) and d(n) are both perfect numbers.
1

%I #11 Dec 15 2017 17:35:53

%S 338,2496,3520,153280,508096,678592,1162432,1461952,2130112,2475712,

%T 2595520,2959552,3042496,3388096,3443392,3581632,3733696,3742912,

%U 3744873,5713173,9492309,11912896,14767353,15009472,18021609,21703125

%N Numbers n such that sopfr(n) and d(n) are both perfect numbers.

%H Donovan Johnson, <a href="/A070311/b070311.txt">Table of n, a(n) for n = 1..300</a>

%o (PARI) {for(n=1,22000000,d=numdiv(n); if(d==sigma(d)-d,s=0; F=factor(n); for(i=1,matsize(F)[1],s=s+F[i,1]*F[i,2]); if(s==sigma(s)-s,print1(n,","))))}

%Y Cf. A000396, A000005, A001414.

%K nonn

%O 1,1

%A _Jason Earls_, May 10 2002

%E More terms from _Klaus Brockhaus_, May 15 2002