OFFSET
1,2
LINKS
Ray Chandler, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harvey P. Dale)
MATHEMATICA
Select[Range[5000], Mod[DivisorSigma[1, #], 4]==1&] (* Harvey P. Dale, Oct 24 2016 *)
PROG
(PARI) isok(n) = ((sigma(n) % 4) == 1);
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jun 19 2002
EXTENSIONS
Name edited by Michel Marcus, Dec 19 2013 and Amiram Eldar, Jun 26 2024
STATUS
approved