login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A091199
Numbers n such that (6n-3)^2 + 2 is prime.
4
1, 2, 3, 4, 6, 7, 8, 10, 14, 17, 18, 19, 20, 21, 25, 29, 37, 38, 40, 41, 42, 43, 46, 50, 51, 52, 54, 58, 59, 61, 62, 63, 65, 70, 71, 72, 74, 75, 76, 80, 84, 86, 92, 93, 94, 96, 101, 102, 109, 113, 114, 117, 119, 126, 130, 135, 137, 140, 145, 148, 150, 151, 152, 156, 160
OFFSET
1,2
COMMENTS
Arises from A056899: primes of the form m^2+2; m should be of the form 6n-3, hence this sequence.
LINKS
FORMULA
a(n) = A056900(n-1) + 1. - Jeppe Stig Nielsen, May 14 2017
EXAMPLE
10 is a member because (60-3)^2 + 2 = 3251 is prime.
MATHEMATICA
Select[ Range[ 163], PrimeQ[(6# - 3)^2 + 2] &] (* Robert G. Wilson v, Feb 26 2004 *)
lst={}; Do[If[PrimeQ[(6n-3)^2+2], AppendTo[lst, n]], {n, 500}]; lst (* Vincenzo Librandi, Jul 16 2012 *)
PROG
(Magma) [n: n in [1..250]| IsPrime((6*n-3)^2+2)]; // Vincenzo Librandi, Jul 16 2012
(PARI) is(n)=isprime((6*n-3)^2+2) \\ Charles R Greathouse IV, May 22 2017
CROSSREFS
Sequence in context: A226038 A181062 A338031 * A093452 A082103 A219618
KEYWORD
easy,nonn
AUTHOR
Zak Seidov, Feb 22 2004
EXTENSIONS
More terms from Ray Chandler and Robert G. Wilson v, Feb 25 2004
STATUS
approved