420419

Properties

Appears in sequences

• Smaller of twin primes whose mean (average) is a multiple of A002110(6)=30030.at n=5A060232
• Numbers n such that n, 2n+1, 3n+2, 4n+3, 5n+4 are primes.at n=14A067258
• Smaller of twin primes of the form P=j*P(i)#-1 and P=j*P(i)#+1 with 0 < j < P(i+1), where P(i) denotes i-th prime and P(i)# the i-th primorial number A002110(i).at n=19A087732
• Safe primes that are also highly cototient numbers.at n=13A209193
• Sophie Germain primes that are also highly cototient numbers.at n=29A209194
• Numbers k such that phi(sigma(k))/k < phi(sigma(m))/m for all m < k, where sigma is the sum of divisors function (A000203) and phi is Euler's totient function (A000010).at n=37A293711
• Numbers k such that phi(psi(k))/k < phi(psi(m))/m for all m < k, where phi is Euler's totient function (A000010) and psi is the Dedekind psi function (A001615).at n=39A293713
• Prime-indexed primes p such that 2*p + 1 is also a prime-indexed prime.at n=34A318294
• Numbers k where records occur for phi(k)/phi(k+1), where phi is the Euler totient function (A000010).at n=33A335070
• Prime numbersat n=35423