21529

Properties

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 98 ones.at n=20A031866
• Primes p for which the period of reciprocal = (p-1)/8.at n=34A056213
• Primes p such that x^36 = 2 has no solution mod p, but x^12 = 2 has a solution mod p.at n=27A059668
• Primes that are each the sum of two, three, and four consecutive composite numbers.at n=26A060339
• Expansion of exp(x)*(1+x)/(1-x)^2.at n=6A082028
• prime(k) for those k where floor((2*(prime(k+1)-prime(k))*PrimePi(k) mod (8*k))/k) = m with m = 8.at n=40A109562
• Primes p such that q-p = 28, where q is the next prime after p.at n=18A124595
• Mother primes of order 11.at n=30A136070
• Numbers of the form prime(prime(prime(k))) with a digit sum which is prime.at n=35A162252
• Least prime p = 1 (mod n) which divides Fibonacci((p-1)/n).at n=22A168171
• Primes of the form x^2 + 7*y^2, where x and y=x+1 are consecutive natural numbers.at n=26A176616
• Prime numbers after which at least four distinct classes modulo 7 are equally represented among the primes to that point.at n=26A217147
• Number of 4 X n -1,1 arrays such that the sum over i=1..4,j=1..n of i*x(i,j) is zero and rows are nondecreasing (ways to put n thrusters pointing east or west at each of 4 positions 1..n distance from the hinge of a south-pointing gate without turning the gate).at n=43A225311
• Number of partitions p of n such that (number of parts of p) - min(p) is not a part of p.at n=37A238548
• Number of n-bit legal binary words with maximal set of 1s.at n=30A253412
• Numbers k such that (265*10^k - 7)/3 is prime.at n=23A266582
• a(n) is the least number such that d(a(n)) = d(R(a(n)))/n, where R(n) is the digit reverse of n and d(n) is the number of divisors of n.at n=17A284495
• Primes equal to a hexagonal number plus 1.at n=27A285790
• Primes of the form k!6+24, where k!6 is the sextuple factorial number (A085158).at n=4A288615
• Numbers that are both prime-indexed primes and lucky-indexed lucky numbers.at n=17A307008