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 A067718 #37 Oct 25 2024 15:38:31 %S A067718 1,2,6,12,24,36,42,70,126,132,144,168,210,225,252,336,344,378,385,396, %T A067718 462,504,528,546,560,561,576,627,630,660,672,693,714,798,896,924,930, %U A067718 945,960,1001,1008,1012,1032,1050,1116 %N A067718 Numbers k such that sigma(2^k+1) == 0 (mod k). %C A067718 1155 is also a term. - _Husnain Raza_, Oct 23 2024 %H A067718 Husnain Raza, <a href="https://github.com/epistemologist/OEIS_Sequences/tree/main/A067718">Github link</a> %t A067718 Select[Range[150], Divisible[DivisorSigma[1, 2^# + 1], #] &] (* _Amiram Eldar_, Nov 28 2020 *) %o A067718 (PARI) isok(n)=sigma(2^n+1)%n==0 \\ _Klaus Brockhaus_, Apr 13 2005 %Y A067718 Cf. A000051, A000203, A069061. %K A067718 nonn,hard,more %O A067718 1,2 %A A067718 _Benoit Cloitre_, Feb 05 2002 %E A067718 a(13)-a(15) from _Klaus Brockhaus_, Apr 13 2005 %E A067718 a(16)-a(21) from _Lars Blomberg_, Jul 28 2017 %E A067718 a(22)-a(44) from _Amiram Eldar_, Nov 28 2020 %E A067718 a(45) from _Husnain Raza_, Sep 18 2024