20113

Properties

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 78 ones.at n=24A031846
• Recip transform of 2*(1 + x^5)-1/(1-x).at n=8A049155
• Numbers n such that n and n+4^k are all primes for k=1,2,3.at n=38A049493
• a(n) and a(n)+4^k are primes at least for k=1,2,3,4.at n=15A049494
• G.f.: ( 1 - x^2 - sqrt( 1 - 2*x^2 - 4*x^3 - 3*x^4 ) ) / ( 2*x^3 ).at n=18A050253
• Euclid-Mullin sequence (A000945) with initial value a(1)=257 instead of a(1)=2.at n=9A051333
• Largest prime factor of 11^n+1 (A034524).at n=12A062308
• Primes whose sum of digits is 7.at n=42A062337
• Initial term in sequence of four consecutive primes separated by 3 consecutive differences each <=6 (i.e., when d=2,4 or 6) and forming d-pattern=[4, 6,6]; short d-string notation of pattern = [466].at n=29A078852
• Primes whose decimal representation is a valid number in base 5 and interpreted as such is again a prime.at n=29A090708
• Primes p such that p + 2^2, p + 4^2 and p + 6^2 are also primes.at n=31A092475
• Numbers k such that 7^k + 5^k - 1 is prime.at n=14A101234
• Primes occurring in A084704 exactly 4 times.at n=7A128655
• Least prime P such that P^(2*prime(n))-P^prime(n)-1 is prime with prime(n) the n-th prime.at n=48A131580
• Primes of the form x^2 + 1848*y^2.at n=54A139668
• Primes of the form 57x^2+18xy+193y^2.at n=34A140631
• Primes congruent to 53 mod 59.at n=38A142780
• Primes congruent to 44 mod 61.at n=35A142842
• Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 1000-1110-0111 pattern in any orientation.at n=10A146816
• Sequence defined by the recurrence formula a(n+1)=sum(a(p)*a(n-p)+k,p=0..n)+l for n>=1, with here a(0)=1, a(1)=9, k=-1 and l=1.at n=6A177200