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%I #6 Aug 31 2020 19:52:24
%S 6,14,15,35,286,470,715,874,969,2001,2185,2261,3021,4669,7049,10509,
%T 24521,30362,34694,34918,46189,54610,58102,58179,62698,65570,69513,
%U 73628,75905,79431,82510,86735,87295,94658,95381,108862,109810,120524,133023,135751,144001,145255,147572,156745,162197,185339,192062,216717
%N Numbers k for which A003973(k) is equal to 2*sigma(k).
%H Antti Karttunen, <a href="/A337384/b337384.txt">Table of n, a(n) for n = 1..600</a>
%H <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%t Select[Range[250000], If[# == 1, 1, DivisorSigma[1, Apply[Times, FactorInteger[#] /. {p_, e_} /; e > 0 :> Prime[PrimePi@ p + 1]^e] ]] == 2 DivisorSigma[1, #] &] (* _Michael De Vlieger_, Aug 27 2020 *)
%o (PARI)
%o A003973(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); sigma(factorback(f)); };
%o isA337384(n) = (A003973(n)==2*sigma(n));
%Y Cf. A000203, A003961, A003973.
%Y Subsequence of A337381.
%K nonn
%O 1,1
%A _Antti Karttunen_, Aug 27 2020
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