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%I #18 Mar 08 2021 22:25:10
%S 2,3,5,7,11,12,13,17,18,19,23,24,29,30,31,37,40,41,42,43,47,48,53,54,
%T 59,60,61,67,71,72,73,79,80,83,84,89,90,96,97,101,103,107,108,109,112,
%U 113,120,126,127,131,132,137,139,140,149,150,151,156,157,160,162
%N Numbers k with property that if k has m divisors, there are m/2 divisors of k whose sum is k.
%C All primes and all numbers of the form 3*2^k (k>1) are terms.
%e 40 is a term because it has 8 divisors and 2+8+10+20 = 40.
%t Select[Range[160], EvenQ[(d = DivisorSigma[0, #])] && MemberQ[Plus @@@ Subsets[Divisors[#], {d/2}], #] &] (* _Amiram Eldar_, Feb 28 2021 *)
%Y Cf. A000203, A293188, A005835.
%K nonn
%O 1,1
%A _Metin Sariyar_, Feb 28 2021