login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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
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 * A350118 A256917 A089144
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 09 2009
EXTENSIONS
Extended by Emeric Deutsch, Jan 20 2009
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 14:13 EDT 2024. Contains 371254 sequences. (Running on oeis4.)