20897

Properties

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 87.at n=13A020426
• Numbers n such that 25*2^n-1 is prime.at n=29A050538
• Lower of twin primes (p,p+2) such that (p*(p+2))^2 + p^2 - (p+2)^2 and (p*(p+2))^2 - p^2 + (p+2)^2 are both prime.at n=2A079812
• Primes p such that p-1 and p+1 are both divisible by fourth powers.at n=12A086709
• Numbers which are primes and which remain prime for three successive applications of incrementing each digit by 2 with carries ignored.at n=24A088787
• Primes p such that p-1 and p+1 are divisible by a fifth power.at n=1A089212
• Primes p such that p + 2, p + 6, and the concatenation p (p+2) (p+6) is prime.at n=7A174858
• Equals one maps: number of n X 3 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..1 n X 3 array.at n=5A220457
• Equals one maps: number of nX6 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..1 nX6 array.at n=2A220460
• T(n,k)=Equals one maps: number of nXk binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..1 nXk array.at n=30A220461
• T(n,k)=Equals one maps: number of nXk binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..1 nXk array.at n=33A220461
• Primes p such that p+2, p+24 and p+246 are also primes.at n=20A235871
• Primes of form n^2 + 2401.at n=17A256835
• Primes p such that prime(p)^2 - 2 = prime(q) for some prime q.at n=20A261354
• Odd numbers k such that the four consecutive odd numbers starting with k have a total of 5 prime factors counting multiplicity.at n=29A328489
• Primes p such that the prime triple (p, p+2 or p+4, p+6) generates a prime number when the digits are concatenated.at n=21A375313
• Difference between pi(2^n) and the integer nearest to 2^n / log(2^n).at n=21A380198
• Prime numbersat n=2350