A063885 z(sigma(n)) = 2n, where z(n) = A048146.
24, 1536, 1631, 47360, 82458
Offset: 1
Programs
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PARI
u(n) = sumdiv(n,d, if(gcd(d,n/d)==1,d)); z(n) = sigma(n)-u(n); for(n=1,10^7, if(z(sigma(n))==2*n,print1(n, ", ")))
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