27997

Properties

Appears in sequences

• 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 15.at n=20A031603
• Numbers k such that 219*2^k+1 is prime.at n=41A032486
• Primes related to the nondecreasing subsequence of A053666.at n=44A069802
• Primes of the form Sum_{k=1..n} phi(prime(k)).at n=17A101302
• Prime numbers p such that pi(p) + 2*p is a square.at n=22A104783
• Primes with digit sum = 34.at n=5A106769
• Smaller member of a pair (p,q) of cousin primes such that p and q are in different centuries.at n=29A160440
• Number of subwords of type dh^ju (j>=1), where u=(1,1), h=(1,0), and d=(1,-1), in all peakless Motzkin paths of length n (can be easily expressed using RNA secondary structure terminology).at n=16A190163
• Smallest number requiring n 1's to build using +, * and -.at n=32A255641
• Primes having only {2, 7, 9} as digits.at n=35A261182
• Primes p such that p^2 + 1 has more divisors than p^2 - 1.at n=15A358879
• Numbers k such that in base 2 the k-th composite is a substring of the k-th prime.at n=17A378479
• Prime numbersat n=3055