18121

Properties

Appears in sequences

• Primes p for which the period of reciprocal = (p-1)/8.at n=29A056213
• First member of a prime quadruple in a 2p-1 progression.at n=11A057327
• Primes with 23 as smallest positive primitive root.at n=7A061335
• Initial term in sequence of four consecutive primes separated by 3 consecutive differences each <=6 (i.e., when d=2,4 or 6) and forming d-pattern=[6, 4,2]; short d-string notation of pattern = [642].at n=23A078855
• Smallest primes starting a complete three iterations Cunningham chain of the second kind.at n=5A110024
• Smallest primes starting a complete three iterations Cunningham chain of the first or second kind.at n=16A110025
• Smallest prime factor of composite Mersenne numbers: lpf(2^p-1) where 2^p-1 is composite and p is prime.at n=23A136030
• Prime numbers p such that p +- ((p-1)/4) are primes.at n=20A137705
• Primes congruent to 48 mod 53.at n=40A142578
• Primes congruent to 8 mod 59.at n=33A142735
• Primes congruent to 4 mod 61.at n=37A142802
• Odd primes which can never divide 2^a+2^b+1.at n=28A179113
• a(n) = n^2 + 731*n + 1.at n=24A180919
• Primes p such that p^2 divides 2^(2^(p-1)-1) - 1.at n=23A188465
• Primes p such that p - 2 and p^3 - 2 are also prime.at n=42A240126
• Primes of the form (k^2+4)/5.at n=29A245042
• Least prime of the form x^2+13*n^2.at n=36A248409
• Non-palindromic balanced primes in base 2.at n=29A256081
• Least prime p such that 2*prime(p*n)+1 = prime(q*n) for some prime q.at n=40A260882
• Five-digit primes whose first, third, and fifth digits are the same.at n=19A269066