OFFSET
1,1
COMMENTS
There are no more terms below 10^9. This sequence is probably complete. - Amiram Eldar, Apr 29 2022
MATHEMATICA
Select[Range[10^5], EulerPhi[#] == 2*DivisorSigma[0, #]^2 &] (* Amiram Eldar, Apr 29 2022 *)
PROG
(Python)
from sympy import totient as phi, divisor_count as tau
def ok(n): return phi(n) == 2*tau(n)**2
print([k for k in range(1, 191521) if ok(k)]) # Michael S. Branicky, Apr 29 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Mar 25 2002
EXTENSIONS
a(37)-a(39) from Amiram Eldar, Apr 29 2022
STATUS
approved