18521

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 54.at n=1A031642
• Numbers k such that 50*R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=12A056686
• Near twin primes of order 18: twin primes (p, p+2) such that p+18 and p+20 are primes.at n=30A079304
• Primes p such that 7 is the largest of all prime factors of the numbers between p and the next prime (cf. A052248).at n=16A080186
• Primes of the form 16*m^2 + 25 for m=1,2,3,...at n=16A087857
• a(0) = 1, a(1) = 2, a(2) = 5; for n >= 3, a(n) = a(n - 1) - 2*a(n - 2) + a(n - 3).at n=34A121311
• Primes p1 such that p1^3+p2^2=pp are average of twin primes. p1 and p2 consecutive primes, p1 < p2.at n=14A138735
• Lesser of twin primes p1 such that p1^3 + p2^2 are average of twin primes. p1 and p2 twin primes, p1 < p2.at n=3A139778
• Primes congruent to 24 mod 53.at n=33A142554
• Primes congruent to 54 mod 59.at n=37A142781
• Primes congruent to 38 mod 61.at n=37A142836
• a(n) = 42*n^2 - 1.at n=20A158626
• List of pairs of twin primes of the form 2k^3 +- 1.at n=2A160518
• A transform of the large Schroeder numbers.at n=12A160823
• Primes p such that p-1 and p+1 each contain at least one cubed prime in their prime factorization.at n=27A162870
• Number of n X n binary matrices that contain no 2 X 2 zero submatrix.at n=4A175563
• Primes of the form 2*k^3-1.at n=5A177105
• a(n) = 54n^3 - 1.at n=6A181968
• The first member of a twin prime pair whose sum equals the sums of two consecutive smaller pairs of twin primes.at n=32A225943
• a(n) = the first member of a twin prime pair whose sum equals the sums of n consecutive pairs of twin primes.at n=39A226719