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Primes p such that p^2-p-1 is prime.
21

%I #17 May 31 2022 06:48:20

%S 3,5,7,11,17,29,31,47,61,67,71,97,101,127,131,139,149,181,197,241,269,

%T 307,331,359,379,397,409,419,421,449,457,479,487,491,599,607,617,619,

%U 641,647,677,709,751,787,839,857,907,947,967,977,997,1051,1061,1091

%N Primes p such that p^2-p-1 is prime.

%D M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988

%D Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta,UTET, CittaStudiEdizioni, Milano 1997

%H T. D. Noe, <a href="/A091567/b091567.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[250]], PrimeQ[ #^2-#-1]&] (* _Alexander Adamchuk_, Jul 27 2006 *)

%o (PARI) isA091567(n)=isprime(n) && isprime(n^2-n-1) \\ _Michael B. Porter_, May 12 2010

%Y Cf. A053182 (p^2+p+1 prime), A053184 (p^2+p-1 prime), A065508 (p^2-p+1 prime).

%Y Cf. A091568 (corresponding primes of the form p^2-p-1).

%K nonn

%O 1,1

%A _T. D. Noe_, Jan 21 2004

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Last modified September 22 16:18 EDT 2024. Contains 376119 sequences. (Running on oeis4.)