23209

Properties

Appears in sequences

• Mersenne exponents: primes p such that 2^p - 1 is prime. Then 2^p - 1 is called a Mersenne prime.at n=25A000043
• Degrees of primitive irreducible trinomials: n such that 2^n - 1 is a Mersenne prime and x^n + x^k + 1 is a primitive irreducible polynomial over GF(2) for some k with 0 < k < n.at n=16A001153
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 96 ones.at n=19A031864
• Primes with 31 as smallest positive primitive root.at n=1A061735
• a(n) = prime(prime(Fibonacci(n))).at n=13A093309
• Primes p = p_(n+1) such that p_n + p_(n+2) = 2*p_(n+1) + 12.at n=24A095673
• a(n) = 5*a(n-1) - a(n-2) for n>1, a(0)=1, a(1)=9.at n=6A099867
• Bisection of A000043.at n=12A099983
• Indices of primes in sequence defined by A(0) = 41, A(n) = 10*A(n-1) - 9 for n > 0.at n=13A101712
• Squares of the norms of Gaussian primes from A107629.at n=37A107630
• Mersenne prime indices that are not Gaussian primes.at n=15A112634
• Zeros in Cald's sequence: positions k such that A006509(k) = 0.at n=11A112877
• Primes with record large values of the second smallest positive primitive root.at n=14A124111
• Primes occurring in A084704 exactly 4 times.at n=10A128655
• Primes p such that 2^p-1 is prime and congruent to 31 mod 5!.at n=14A145040
• Primes p (A000043) such that 2^p-1 is prime (A000668) and congruent to 271 mod 6!.at n=4A145044
• Base-2 logarithm of A136007(n)+1.at n=17A152961
• Isolated primes p such that 2^p-1 is also a prime number.at n=13A161676
• Odd Mersenne exponents.at n=24A174265
• Numbers k such that exactly one of 2^k - 1 and 2^k + 1 is a prime.at n=29A174269