683929
domain: N
Appears in sequences
- Numbers whose sum of divisors is prime.at n=32A023194
- Squares that are the concatenation of three numbers, one of which is the sum of the other two.at n=17A062555
- Numbers k such that the sum of the cubes of divisors of k is a prime.at n=8A063783
- Numbers k that require four iterations of the sigma function to be >= 2*k.at n=15A107914
- Squares of lesser of twin primes.at n=32A108570
- Six-digit squares that are concatenation of two 3-digit primes.at n=13A153050
- Odd numbers N for which numerator(sigma(N)/N) is a prime.at n=27A193065
- Numbers k such that tau(sigma(tau(k))) = sigma(tau(sigma(k))), where tau is A000005 and sigma is A000203.at n=22A237613
- Squares s such that s + 1234567890 is prime.at n=28A241538
- Numbers n such that 2n-1 and sigma(n) are both primes.at n=17A249902
- Perfect powers m^k such that m, k and m+k are primes.at n=36A258400
- Prime powers p^k such that p^k = x^3 + y^3 + z^3 where x, y, z are positive integers and k > 1, is soluble.at n=28A271829
- Odd squares not of the form p + 2^k with p prime.at n=10A276567
- Odd numbers with prime sum of divisors.at n=25A278911
- Numbers m such that m! / sigma(m) is not an integer.at n=33A325436
- Numbers k for which A348717(k) is a multiple of A348717(sigma(k)).at n=38A364131