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%I #9 Mar 01 2014 09:10:58
%S 18,20,52,57,70,381,426,543,1252,3027,4098,4612,6807,257799,302403,
%T 1583607,3272727,52859523,20402085927
%N Numbers n such that phi(n) = sigma(sum of distinct prime factors of n).
%e phi(52) = 24; sigma(sum of prime factors of 52) = sigma(15) = 24. Hence 52 belongs to the sequence.
%t Select[Range[2, 10^5], DivisorSigma[1, Apply[Plus, Transpose[FactorInteger[ # ]][[1]]]] == EulerPhi[ # ] &]
%Y Cf. A000010, A000203, A008472.
%K nonn
%O 1,1
%A _Joseph L. Pe_, Oct 15 2002
%E a(14)-a(18) from _Donovan Johnson_, Jun 06 2009
%E Name clarified, offset corrected, term a(19) added, _Donovan Johnson_, Mar 01 2014
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