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A164041
Primes of the form 2*p^2 + 4*p + 1, where p is also prime.
2
17, 31, 71, 127, 647, 1151, 2887, 3527, 7687, 12799, 19207, 20807, 23327, 34847, 39199, 49927, 53791, 73727, 79999, 103967, 117127, 145799, 172871, 194687, 220447, 279751, 294911, 323207, 336199, 387199, 394271, 419527, 438047, 587527, 649799, 724807
OFFSET
1,1
COMMENTS
A subsequence of the primes of the form 2k^2+4k+1 = 2*(k+1)^2-1, A066436. - R. J. Mathar, Aug 10 2009
LINKS
FORMULA
a(n) = 2*(A164042(n))^2 + 4*A164042(n) + 1.
MATHEMATICA
lst={}; Do[p=Prime@n; a=2*p^2+4*p+1; If[PrimeQ@a, AppendTo[lst, a]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 12 2009 *)
Select[Table[2p^2+4p+1, {p, Prime[Range[200]]}], PrimeQ] (* Harvey P. Dale, Aug 25 2019 *)
PROG
(Magma) [a: p in PrimesUpTo(700)|IsPrime(a) where a is 2*p^2+4*p+1 ] // Vincenzo Librandi, Sep 01 2012
(PARI) lista(nn) = {forprime(p=2, nn, if(isprime(q=2*p^2+4*p+1), print1(q, ", "))); } \\ Altug Alkan, Mar 29 2018
CROSSREFS
Sequence in context: A087166 A167496 A370851 * A085598 A163443 A339181
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Aug 08 2009
EXTENSIONS
a(29) corrected by R. J. Mathar, Aug 11 2009
Edited by N. J. A. Sloane, Aug 11 2009
STATUS
approved