A091568 - OEIS

A091568

Primes of the form p^2 - p - 1, where p is prime.

5, 19, 41, 109, 271, 811, 929, 2161, 3659, 4421, 4969, 9311, 10099, 16001, 17029, 19181, 22051, 32579, 38611, 57839, 72091, 93941, 109229, 128521, 143261, 157211, 166871, 175141, 176819, 201151, 208391, 228961, 236681, 240589, 358201, 367841

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OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..5000

MATHEMATICA

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 *)

Select[#^2-#-1&/@Prime[Range[200]], PrimeQ] (* Harvey P. Dale, May 15 2016 *)

PROG

(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

CROSSREFS

Cf. A091567 (p such that p^2 - p - 1 is prime).

Sequence in context: A119534 A306190 A033622 * A147307 A234801 A089148

Adjacent sequences: A091565 A091566 A091567 * A091569 A091570 A091571

KEYWORD

nonn

AUTHOR

T. D. Noe, Jan 21 2004

STATUS

approved