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Numbers such that all sums of two distinct divisors are not divisors.
3

%I #9 Aug 31 2019 06:25:36

%S 1,2,3,4,5,7,8,9,10,11,13,14,15,16,17,19,21,22,23,25,26,27,28,29,31,

%T 32,33,34,35,37,38,39,41,43,44,45,46,47,49,50,51,52,53,55,57,58,59,61,

%U 62,63,64,65,67,68,69,71,73,74,75,76,77,79,81,82,83,85,86,87,88,89,91

%N Numbers such that all sums of two distinct divisors are not divisors.

%H Amiram Eldar, <a href="/A094520/b094520.txt">Table of n, a(n) for n = 1..10000</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Sum-FreeSet.html">Sum-Free Set</a>

%F A094518(a(n)) = 0.

%t aQ[n_] := AllTrue[Total /@ Subsets[Divisors[n], {2}], ! Divisible[n, #] &]; Select[Range[91], aQ] (* _Amiram Eldar_, Aug 31 2019 *)

%Y Cf. A094518.

%Y Complement of A094519.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, May 06 2004