OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
tau(4^2) = tau(16) = 5 (prime).
MAPLE
N:= 1000: # to get all terms <= N
es:= select(t -> isprime(2*t+1), [$1..ilog2(N)]):
Ps:= select(isprime, [2, seq(i, i=3..N, 2)]):
sort(select(`<=`, [seq(seq(p^e, e=es), p=Ps)], N)): # Robert Israel, Mar 16 2017
MATHEMATICA
Select[Range@ 227, PrimeQ[DivisorSigma[0, #^2]] &] (* Michael De Vlieger, Mar 09 2017 *)
PROG
(Magma) [n: n in [2..100000] | IsPrime(NumberOfDivisors(n^2))]
(PARI) for(n=1, 227, if(isprime(numdiv(n^2)), print1(n, ", "))) \\ Indranil Ghosh, Mar 09 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Mar 08 2017
STATUS
approved