OFFSET
1,2
COMMENTS
1155 is also a term. - Husnain Raza, Oct 23 2024
LINKS
Husnain Raza, Github link
MATHEMATICA
Select[Range[150], Divisible[DivisorSigma[1, 2^# + 1], #] &] (* Amiram Eldar, Nov 28 2020 *)
PROG
(PARI) isok(n)=sigma(2^n+1)%n==0 \\ Klaus Brockhaus, Apr 13 2005
CROSSREFS
KEYWORD
nonn,hard,more,changed
AUTHOR
Benoit Cloitre, Feb 05 2002
EXTENSIONS
a(13)-a(15) from Klaus Brockhaus, Apr 13 2005
a(16)-a(21) from Lars Blomberg, Jul 28 2017
a(22)-a(44) from Amiram Eldar, Nov 28 2020
a(45) from Husnain Raza, Sep 18 2024
STATUS
approved