28393

Properties

Appears in sequences

• Sextan primes: p = (x^6 + y^6)/(x^2 + y^2).at n=34A002647
• Cyclotomic polynomials at x=13.at n=12A019331
• Cyclotomic polynomials at x=-13.at n=12A020512
• 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 25.at n=6A031613
• Primes whose consecutive digits differ by 5 or 6.at n=20A048417
• a(n) = n^4 - n^2 + 1.at n=13A060886
• Primes with 15 as smallest positive primitive root.at n=6A061328
• Primes of the form sigma_4(k)/sigma_2(k), arising in A066109.at n=4A066110
• Greatest prime factor of prime(n)^n+1.at n=5A069463
• Primes for which the smallest positive primitive root is odd and nonprime.at n=12A070269
• a(n) = sigma_4(n^2)/sigma_2(n^2).at n=12A084218
• Resultant of the polynomial x^3-1 and the Chebyshev polynomial of the first kind T_n(x).at n=6A085640
• Primes of the form 16*m^2 + 169, m=1,2,3,...at n=14A087862
• Primes of the form 12k+1 generated recursively. Initial prime is 13. General term is a(n)=Min {p is prime; p divides Q^4-Q^2+1}, where Q is the product of previous terms in the sequence.at n=1A124990
• Smallest prime divisor of n^4-n^2+1.at n=11A125258
• a(n) = 42*n^2 + 1.at n=26A158604
• Prime p1 of consecutive primes p1, p2, where p2-p1=10, and p1, p2 are in different centuries.at n=32A160500
• Primes p such that there are positive integers m and n and a prime q such that p = m^2+m-q = n^2+n+q.at n=27A162652
• Primes of the form ((p-1)/2)^2+((p+1)/2), where p is prime.at n=28A163418
• Noncomposite numbers in the southwestern ray of the Ulam spiral as oriented on the March 1964 cover of Scientific American.at n=21A168026