A248719 Numbers n such that 4*nextprime(2^n)^2+1 is prime.
0, 1, 2, 5, 6, 18, 43, 52, 106, 383, 417, 663, 849, 971
Offset: 1
Keywords
Examples
a(1)=0 since nextprime(2^0)=2 and 4*2^2+1 = 17 is prime.
Crossrefs
Cf. A174246.
Programs
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Mathematica
fQ[n_] := PrimeQ[ 4NextPrime[2^n]^2 + 1]; Select[ Range@ 3000, fQ] (* Robert G. Wilson v, Dec 27 2014 *)
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PARI
for(n=0,9e9,ispseudoprime(4*nextprime(2^n)^2+1)&&print1(n","))
Extensions
a(13) and a(14) from Robert G. Wilson v, Dec 27 2014
Comments