253541929

Appears in sequences

• Numbers n such that sigma(n) and sigma(n^2) are primes.at n=17A232444
• Numbers k such that sigma(k), sigma(k^2) and sigma(k^3) are primes.at n=3A299147
• Numbers k such that sigma(k) and sigma(k^3) are both primes.at n=20A299153