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 A354714 #11 Jun 04 2022 09:46:08 %S A354714 1,15,27,35,39,51,55,87,91,95,111,115,119,123,135,143,155,159,183,187, %T A354714 203,215,219,231,235,245,247,255,259,267,275,287,291,295,299,303,319, %U A354714 323,327,335,339,343,351,355,371,375,391,395,399,403,407,411,415,425,427,447,451,455,471,511,515 %N A354714 Nonprime numbers k such that the number of divisors of k divides k+1. %C A354714 Nonprime numbers k such that k == -1 (mod A000005(k)). %t A354714 Select[Range[500], ! PrimeQ[#] && Divisible[# + 1, DivisorSigma[0, #]] &] (* _Amiram Eldar_, Jun 03 2022 *) %Y A354714 Nonprime terms of A272872. %Y A354714 Cf. A000005, A033950, A354711, A354712, A354715, A354716. %K A354714 nonn %O A354714 1,2 %A A354714 _Max Alekseyev_, Jun 03 2022