OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..300
MATHEMATICA
Select[Range[0, 400000], IntegerQ[Sqrt[DivisorSigma[1, #^2+1]]]&] (* Harvey P. Dale, May 14 2018 *)
PROG
(PARI) for(n=0, 500000, if(issquare(sigma(n^2+1)), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 23 2002
EXTENSIONS
More terms from Rick L. Shepherd, Apr 16 2002
STATUS
approved