491401

Appears in sequences

• Squares whose digits are squares.at n=26A019544
• Numbers whose sum of divisors is prime.at n=27A023194
• a(n) = n*(n+1)*(n+2)*(n+3)+1 = (n^2 + 3*n + 1)^2.at n=25A062938
• Numbers k such that sigma_4(k)/sigma_2(k) is prime.at n=34A066109
• Numbers n such that n and sigma(n) are prime powers (of the form p^k, p prime, k>=1).at n=34A071114
• Squares of A052918(n-1) (generalized Fibonacci).at n=5A099365
• Numbers k that require four iterations of the sigma function to be >= 2*k.at n=11A107914
• "Binary prime squares": squares whose binary expansions, read as decimal expansions, are primes.at n=23A108324
• Six-digit squares that are concatenation of two 3-digit primes.at n=11A153050
• Odd numbers N for which numerator(sigma(N)/N) is a prime.at n=22A193065
• Composite numbers with both 10 and -10 as primitive root.at n=26A218766
• Numbers n such that (the sum of the divisors of n) plus (the sum of the squares of the divisors of n) plus (the sum of the cubes of the divisors of n) is a prime number.at n=22A220586
• Numbers k such that tau(sigma(tau(k))) = sigma(tau(sigma(k))), where tau is A000005 and sigma is A000203.at n=18A237613
• Numbers n such that 2n-1 and sigma(n) are both primes.at n=14A249902
• Odd numbers with prime sum of divisors.at n=20A278911
• Numbers n such that the number of divisors of sum of divisors of n is prime.at n=37A281882
• Composite numbers k such that tau(k^(k-1)) is a prime.at n=48A283549
• Numbers m such that m! / sigma(m) is not an integer.at n=28A325436
• Numbers k for which A348717(k) is a multiple of A348717(sigma(k)).at n=33A364131