A028886 Primes of the form k^2 - 8.

17, 41, 73, 113, 281, 353, 433, 521, 617, 953, 1217, 1361, 2017, 2393, 2593, 2801, 4217, 4481, 6553, 7561, 8273, 8641, 10193, 10601, 13217, 13681, 14153, 14633, 15121, 16633, 17681, 18217, 20441, 21017, 21601, 22193, 25913, 26561, 29921, 31321, 34217, 34961, 36473

Offset

1,1

Comments

Primes of A028884. Also subsequence of A038873. - Klaus Purath, Jan 28 2020

Conjecture: (2*m+1)^2 - 8 for m > 2 is prime iff q*(m+1) + binomial(q,2) + 1 is never a square for 1 <= q <= 2*(m-2). - Mikhail Kurkov, Dec 18 2025

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..8000

Patrick De Geest, Palindromic Quasipronics of the form n(n+x).

Mathematica

Select[Range[3, 1000]^2-8, PrimeQ] (* Vincenzo Librandi, Dec 01 2011 *)

Prog

(Magma) [a: n in [3..300] | IsPrime(a) where a is n^2-8]; // Vincenzo Librandi, Dec 01 2011

Crossrefs

Cf. A028884, A038873.

Sequence in context: A138005 A267421 A166147 * A146443 A110226 A054819

Adjacent sequences: A028883 A028884 A028885 * A028887 A028888 A028889

Keyword

nonn,easy

Author

Patrick De Geest

Status

approved