180179

Properties

Appears in sequences

• Primes whose decimal expansion is a concatenation of two or more consecutive decreasing numbers (no leading zeros allowed).at n=22A052088
• Primes formed by concatenating k with k-1.at n=20A052089
• Smaller of twin primes whose middle term is a multiple of A002110(5)=2310.at n=14A060231
• Smaller of twin primes whose mean (average) is a multiple of A002110(6)=30030.at n=0A060232
• Smaller of twin primes {p, p+2} whose average p+1 = k*q is the least multiple of the n-th primorial number q such that k*q-1 and k*q+1 are twin primes.at n=5A060255
• 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=14A087732
• a(n) = A126098(n) - 1.at n=27A117010
• Safe primes that are also highly cototient numbers.at n=11A209193
• The lesser of twin primes p1 such that 2*p1 + p2 is a prime number (A174913) and also the lesser of other twin primes in A174913.at n=10A242772
• Primes of the form A060735(k) +- 1, where A060735 lists multiples of primorials (A002110) less than the next larger primorial.at n=46A257658
• 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=31A293711
• 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=33A293713
• Numbers k where records occur for phi(k)/phi(k+1), where phi is the Euler totient function (A000010).at n=27A335070
• a(n) is the least number whose sum of digits in primorial base equals n.at n=40A343048
• Prime numbersat n=16354