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 A069169 #12 Apr 30 2022 08:01:55
%S A069169 1,6,10,14,15,18,21,22,26,28,30,33,34,35,38,39,40,42,46,51,52,55,57,
%T A069169 58,62,65,66,69,70,74,76,77,78,82,84,85,86,87,90,91,93,94,95,102,105,
%U A069169 106,110,111,114,115,118,119,120,122,123,124,126,129,130,133,134,138,140
%N A069169 Nonprimes k such that sigma(k)*Sum_{d|k} 1/sigma(d) is an integer.
%H A069169 Amiram Eldar, <a href="/A069169/b069169.txt">Table of n, a(n) for n = 1..10000</a>
%t A069169 q[n_] := IntegerQ[DivisorSigma[1, n]*DivisorSum[n, 1/DivisorSigma[1, #] &]]; Select[Range[140], !PrimeQ[#] && q[#] &] (* _Amiram Eldar_, Apr 30 2022 *)
%o A069169 (PARI) isok(k) = !isprime(k) && (denominator(sigma(k)*sumdiv(k, d, 1/sigma(d))) == 1); \\ _Michel Marcus_, Apr 30 2022
%Y A069169 Cf. A000203, A265709, A265710.
%K A069169 easy,nonn
%O A069169 1,2
%A A069169 _Benoit Cloitre_, Apr 09 2002