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%I A325380 #10 Jun 18 2019 07:24:18
%S A325380 801,1377,1773,2525,3725,4689,4753,6309,6425,7209,7677,8577,8957,9477,
%T A325380 11133,11225,11493,11925,12393,12429,12789,13077,15381,15777,18873,
%U A325380 19269,19845,20025,20629,21213,24201,26073,26721,28037,28989,29277,29961,30037,30213,31925,32553,33273,34425,34677,36369,36441,38725,39249,40329
%N A325380 Numbers k in A228058 such that also A001065(k) is in A228058.
%C A325380 If any odd perfect number exists, then it must occur in this sequence.
%H A325380 Antti Karttunen, <a href="/A325380/b325380.txt">Table of n, a(n) for n = 1..10000</a>
%H A325380 <a href="/index/O#opnseqs">Index entries for sequences where any odd perfect numbers must occur</a>
%o A325380 (PARI)
%o A325380 A001065(n) = (sigma(n)-n);
%o A325380 isA228058(n) = if(!(n%2)||(omega(n)<2),0,my(f=factor(n),y=0); for(i=1,#f~,if(1==(f[i,2]%4), if((1==y)||(1!=(f[i,1]%4)),return(0),y=1), if(f[i,2]%2, return(0)))); (y));
%o A325380 k=0; n=0; while(k<100,n++; if(isA228058(n)&&isA228058(A001065(n)), k++; print1(n,", ")));
%Y A325380 Cf. A001065, A228058, A325377.
%K A325380 nonn
%O A325380 1,1
%A A325380 _Antti Karttunen_, Apr 22 2019

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