A174281 Primes p such that 20*p^2+32*p+13 is also prime.
2, 5, 7, 17, 19, 23, 29, 47, 73, 83, 89, 97, 107, 113, 127, 137, 149, 163, 197, 227, 229, 233, 239, 257, 269, 307, 359, 367, 373, 379, 439, 449, 557, 569, 619, 647, 673, 727, 739, 769, 797, 827, 877, 883, 919, 977, 983, 997, 1009, 1033, 1039, 1087, 1117, 1123
Offset: 1
Examples
For p=2, 20*2^2+32*2+13=157; p=5, 20*5^2+32*5+13=673.
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Crossrefs
Cf. A154414.
Programs
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Magma
[p: p in PrimesUpTo(2000)| IsPrime(20*p^2+32*p+13)];
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Mathematica
Select[Prime[Range[200]], PrimeQ[20 #^2 + 32 # + 13]&] (* Vincenzo Librandi, Apr 16 2013 *)