This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A094520 #16 Apr 20 2025 02:36:11
%S A094520 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 A094520 32,33,34,35,37,38,39,41,43,44,45,46,47,49,50,51,52,53,55,57,58,59,61,
%U A094520 62,63,64,65,67,68,69,71,73,74,75,76,77,79,81,82,83,85,86,87,88,89,91
%N A094520 Numbers such that all sums of two distinct divisors are not divisors.
%C A094520 The numbers of terms that do not exceed 10^k, for k = 1, 2, ..., are 9, 78, 770, 7683, 76799, 767791, 7677080, 76767834, 767667691, 7676629816, ... . Apparently, the asymptotic density of this sequence exists and equals 0.76766... . - _Amiram Eldar_, Apr 20 2025
%H A094520 Amiram Eldar, <a href="/A094520/b094520.txt">Table of n, a(n) for n = 1..10000</a>
%H A094520 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Sum-FreeSet.html">Sum-Free Set</a>.
%F A094520 A094518(a(n)) = 0.
%t A094520 aQ[n_] := AllTrue[Total /@ Subsets[Divisors[n], {2}], ! Divisible[n, #] &]; Select[Range[91], aQ] (* _Amiram Eldar_, Aug 31 2019 *)
%o A094520 (PARI) isok(k) = {my(d = divisors(k)); for(i = 1, #d, for(j = 1, i-1, if(!(k % (d[i] + d[j])), return(0)))); 1;} \\ _Amiram Eldar_, Apr 20 2025
%Y A094520 Cf. A094518.
%Y A094520 Complement of A094519.
%K A094520 nonn
%O A094520 1,2
%A A094520 _Reinhard Zumkeller_, May 06 2004