21499

Properties

Appears in sequences

• Last member of a sexy prime quadruple: value of p+18 such that p, p+6, p+12 and p+18 are all prime.at n=36A046124
• Numbers k such that in the ring Z[sqrt(3)] the norm of (-1+sqrt(3))^k-1 is prime.at n=16A067834
• Primes p(x) satisfying the following conditions: (a) A082882(x)=1; (b) {p(x),p(x+1)} are not twin primes; (c) values of A075860(j) for j composites between these two non-twin primes are identical.at n=10A082883
• Smallest odd prime base q such that p^3 divides q^(p-1) - 1, where p = prime(n).at n=19A125637
• Primes p, with index k, such that p-k and p+k are both prime.at n=30A143794
• Smaller member of a pair (p,q) of cousin primes such that p and q are in different centuries.at n=21A160440
• Smallest number k such that the continued fraction expansion of sqrt(k) contains n distinct numbers.at n=27A187142
• Primes of the form k!6-6, where k!6 is the sextuple factorial number (A085158).at n=2A289727
• Number of equivalence classes of convex lattice polygons of genus n.at n=14A322343
• Prime numbersat n=2412