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 A383392 #13 May 01 2025 22:33:41
%S A383392 1,3,14,19,27,28,48,139,164,243,496,1428,1440,3360,3480,5932,8128,
%T A383392 11004,19683,25296,27144,31756,35616,45436,47520,51480,84000,115506,
%U A383392 218520,221088,288288,290520,303309,414528,445788,605880,1019070,1122432,2100000,2136288
%N A383392 Numbers k such that (sigma(k) + sigma(k + sigma(k))) / k is an integer where sigma(k) = A000203(k) is the sum of the divisors of k.
%e A383392 k = 3: (sigma(3) + sigma(3 + sigma(3)))/3 = (4 + 8)/3 = 4.
%t A383392 q[k_] := Module[{s = DivisorSigma[1, k]}, Divisible[s + DivisorSigma[1, k + s], k]]; Select[Range[2200000], q] (* _Amiram Eldar_, Apr 25 2025 *)
%o A383392 (PARI) isok(k) = my(s=sigma(k)); ((s+sigma(k+s)) % k) == 0; \\ _Michel Marcus_, Apr 25 2025
%Y A383392 Cf. A000203, A007691, A246456.
%K A383392 nonn
%O A383392 1,2
%A A383392 _Ctibor O. Zizka_, Apr 25 2025