A164042 Primes p such that 2*p^2+4*p+1 is also prime.
2, 3, 5, 7, 17, 23, 37, 41, 61, 79, 97, 101, 107, 131, 139, 157, 163, 191, 199, 227, 241, 269, 293, 311, 331, 373, 383, 401, 409, 439, 443, 457, 467, 541, 569, 601, 607, 619, 653, 709, 719, 773, 839, 853, 881, 929, 947, 983, 1031, 1063, 1087, 1097, 1109, 1153, 1231, 1249
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Crossrefs
Cf. A164041.
Programs
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Magma
[p: p in PrimesUpTo(1500) | IsPrime(2*p^2+4*p+1)]; // Vincenzo Librandi, Apr 08 2013
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Mathematica
lst={}; Do[p=Prime@n; a=2*p^2+4*p+1; If[PrimeQ@a,AppendTo[lst,p]],{n,7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 12 2009 *) Select[Range[2000], PrimeQ[#]&&PrimeQ[2 #^2 + 4 # + 1]&] (* Vincenzo Librandi, Apr 08 2013 *) Select[Prime[Range[250]],PrimeQ[2#^2+4#+1]&] (* Harvey P. Dale, Sep 06 2022 *)
Extensions
Extended by R. J. Mathar, Aug 11 2009
Comments