21929

Properties

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 87.at n=15A020426
• Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 59.at n=0A031647
• Starting positions of strings of three 4's in the decimal expansion of Pi.at n=15A083615
• Numbers k such that k + sum_of_digits(k) is a cube.at n=26A084661
• Primes p such that 8p +1 and (p-1)/8 are primes.at n=12A085958
• Primes of the form 16*m^2 + 25, m=1,3,5,...at n=9A087856
• Primes of the form 16*m^2 + 25 for m=1,2,3,...at n=17A087857
• a(n) = min{ m : sum_{n <= i <= m} 1/p_i > 1}, where p_i is the i-th prime = A000040(i).at n=23A092325
• Smallest prime for which 2^n exactly divides the class number h(-4p).at n=7A102264
• Intersection of A061068 and A064270.at n=36A128996
• Father primes of order 8.at n=34A136077
• Primes congruent to 40 mod 59.at n=38A142767
• Primes dividing some member of A073833.at n=38A161500
• Primes of the form 3*k^2 + 9*k + 5.at n=32A171838
• Primes p such that 2*p^4-+21 are also prime.at n=31A174367
• Smallest prime q such that 2*prime(n)*q^prime(n)-1 is also prime.at n=49A225724
• a(n) = number of steps to reach 0 when starting from k = n^3 and repeatedly applying the map that replaces k with k - A055401(k), where A055401(k) = the number of positive cubes needed to sum to k using the greedy algorithm.at n=57A261227
• Prime time primes (of the form HMMSS with primes H < 24 and MM, SS < 60) such that the corresponding number of seconds after midnight is also prime.at n=13A295000
• Primes p such that A001177(p) = (p-1)/8.at n=40A308801
• Numbers k such that (11^k + 6^k)/17 is prime.at n=5A338525