OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
n=5: n^2=25, sigma(25)=25+5+1=31, 2*25=50, abundance=-19.
MATHEMATICA
Select[Range[170], PrimeQ[DivisorSigma[1, #^2] - 2*#^2] &] (* Amiram Eldar, Sep 23 2019 *)
PROG
(PARI) for(n=1, 170, if(isprime(abs(sigma(n^2)-2*n^2)), print1(n, ", "))) \\ Klaus Brockhaus, Nov 25 2006
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason G. Wurtzel, Nov 25 2006
EXTENSIONS
More terms from Klaus Brockhaus, Nov 25 2006
STATUS
approved