OFFSET
1,1
COMMENTS
LINKS
T. D. Noe, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = A278911(n)^(1/2). - Robert Israel, Jan 22 2019
MATHEMATICA
Select[Range[1, 2401, 2], PrimeQ[DivisorSigma[1, #^2]]&] (* Harvey P. Dale, Mar 07 2015 *)
PROG
(PARI) forstep(N=1, 1e7, 2, isprime(sigma(N^2)) && print1(N", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Jul 15 2011
STATUS
approved