|
%I #15 May 15 2016 08:51:11
%S 5,19,41,109,271,811,929,2161,3659,4421,4969,9311,10099,16001,17029,
%T 19181,22051,32579,38611,57839,72091,93941,109229,128521,143261,
%U 157211,166871,175141,176819,201151,208391,228961,236681,240589,358201,367841
%N Primes of the form p^2 - p - 1, where p is prime.
%H Vincenzo Librandi, <a href="/A091568/b091568.txt">Table of n, a(n) for n = 1..5000</a>
%t lst={};Do[p=Prime[n];p=p^2-p-1;If[PrimeQ[p],AppendTo[lst,p]],{n,3*5!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jan 27 2009 *)
%t Select[#^2-#-1&/@Prime[Range[200]],PrimeQ] (* _Harvey P. Dale_, May 15 2016 *)
%o (PARI) isA091568(n)={local(i);i=floor((1/2)+sqrt(n+(5/4)));isprime(i) && n==i^2-i-1 && isprime(n)} \\ _Michael B. Porter_, May 12 2010
%Y Cf. A091567 (p such that p^2 - p - 1 is prime).
%K nonn
%O 1,1
%A _T. D. Noe_, Jan 21 2004
|
