A354714 - OEIS

%I #11 Jun 04 2022 09:46:08

%S 1,15,27,35,39,51,55,87,91,95,111,115,119,123,135,143,155,159,183,187,

%T 203,215,219,231,235,245,247,255,259,267,275,287,291,295,299,303,319,

%U 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 Nonprime numbers k such that the number of divisors of k divides k+1.

%C Nonprime numbers k such that k == -1 (mod A000005(k)).

%t Select[Range[500], ! PrimeQ[#] && Divisible[# + 1, DivisorSigma[0, #]] &] (* _Amiram Eldar_, Jun 03 2022 *)

%Y Nonprime terms of A272872.

%Y Cf. A000005, A033950, A354711, A354712, A354715, A354716.

%K nonn

%O 1,2

%A _Max Alekseyev_, Jun 03 2022