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A154431 Primes p such that 5p^2 - p + 1 is prime. 2
2, 3, 7, 17, 19, 29, 43, 73, 107, 199, 229, 359, 397, 409, 443, 449, 479, 563, 593, 607, 617, 677, 787, 887, 953, 1013, 1069, 1087, 1109, 1213, 1277, 1279, 1283, 1367, 1409, 1549, 1613, 1627, 1667, 1759, 1867, 1877, 1993, 2003, 2129, 2269, 2297, 2423, 2539 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

For p=2,   5p^2 - p + 1 = 19 (a prime);

for p=107, 5p^2 - p + 1 = 57139 (a prime);

for p=199, 5p^2 - p + 1 = 197807 (a prime).

MAPLE

a:= proc (n) if isprime(n) and isprime(5*n^2-n+1) then n end if end proc: seq(a(n), n = 2 .. 3000); # Emeric Deutsch, Jan 20 2009

MATHEMATICA

Select[Prime[Range[1000]], PrimeQ[(5#^2 - # + 1)] &] (* Vincenzo Librandi, Oct 14 2012 *)

PROG

(MAGMA) [p: p in PrimesUpTo(3000)|IsPrime(5*p^2 - p + 1)]; // Vincenzo Librandi, Oct 14 2012

CROSSREFS

Cf. A154432.

Sequence in context: A077322 A174359 A160513 * A256917 A089144 A045332

Adjacent sequences:  A154428 A154429 A154430 * A154432 A154433 A154434

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Jan 09 2009

EXTENSIONS

Extended by Emeric Deutsch, Jan 20 2009

STATUS

approved

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Last modified May 20 02:49 EDT 2019. Contains 323412 sequences. (Running on oeis4.)