A063870 Numbers n such that sigma(n) - usigma(n) = 3n/2.
480, 2688, 2095104, 16854816, 41055200, 1839272960, 5905219584, 204004720640
Offset: 1
Keywords
Programs
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PARI
u(n) = sumdiv(n,d, if(gcd(d,n/d)==1,d)); for(n=1,10000, if(sigma(n)-u(n)==3*n/2,print(n)))
Extensions
More terms from Dean Hickerson, Sep 25 2001
There are no others less than 1.5*10^13, but here's a larger one: 948990933336933380096. - Dean Hickerson, Sep 25 2001