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A307961
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The number of coreful perfect numbers (A307958) below 10^n.
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2
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) ~ c * 10^n, were c = 0.009361... is the asymptotic density of the coreful perfect numbers (A307960).
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MATHEMATICA
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f[p_, e_] := (p^(e+1)-1)/(p-1)-1; csigma[1]=1; csigma[n_] := Times @@ (f @@@ FactorInteger[n]); cpQ[n_] := csigma[n] == 2*n; s={}; c=0; p=100; Do[If[k==p, AppendTo[s, c]; p*=10]; If[cpQ[k], c++], {k, 1, 1000001}]; s
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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