19913

Properties

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 75.at n=19A020414
• Primes that remain prime through 3 iterations of function f(x) = 3x + 4.at n=12A023278
• Numbers n such that 9^n - 8^n is prime or a strong pseudoprime.at n=8A059803
• Value of C in y = x^2 + 5x + C such that y is prime for all x = 0 to 3.at n=40A097434
• Primes p such that p's set of distinct digits is {1,3,9}.at n=35A108383
• Primes p such that q = p+d (with d >= 6) is the next prime and both p and q are Sophie Germain primes.at n=33A128825
• Base-2 logarithm of (n-th even superperfect number divided by 2^n), plus 1.at n=23A134713
• Primes congruent to 27 mod 61.at n=37A142825
• a(n) is the smallest prime prime(k) > a(n-1) such that the n numbers 2*prime(j)+3, j=k to k+n-1, are all prime.at n=4A190478
• Number of lower triangles of an n X n 0..4 array with no element greater than the number its nonzero horizontal and vertical neighbors.at n=3A195951
• Emirps whose internal digits are also an emirp.at n=25A225235
• Prime numbers P such that 8*P^2-1 and 8*(8*P^2-1)^2-1 are also prime numbers.at n=31A245674
• Number of polynomials a_k*x^k + ... + a_1*x + a_0 with k > 0, integer coefficients and only non-multiple positive integer roots and a_0 = p^n (p is a prime).at n=41A248956
• Least number of steps required in 2D prime walk for it to cross itself n times.at n=8A268463
• Number of binary necklaces of length n with no subsequence 00000.at n=18A280303
• Where the prime race among 9k+1, ..., 9k+8 changes leader.at n=44A297407
• Numbers at the start of a run of 2 or more consecutive primes that are Sophie Germain primes.at n=34A339474
• Numbers at the start of a run of exactly 2 consecutive primes that are Sophie Germain primes.at n=33A339475
• a(n) = Sum_{1 <= i <= j <= k <= n} gcd(i,j,k).at n=42A344521
• Beginning with 11, least prime such that concatenation of first n terms and its digit reversal both are primes.at n=26A380227