1988100

Appears in sequences

• Squares s(n) such that cube(n)-square(n)-1 and cube(n)+square(n)+1 are primes.at n=31A155931
• Numbers k such that phi(k)^phi(k) == 1 (mod sigma(k)).at n=24A248861
• Numbers k such that sigma(k) - 3k is prime.at n=19A306492