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%I #19 Sep 08 2022 08:45:17
%S 1,2,3,4,5,6,8,10,14,22,38,42,71,118,128,159,179,214,484,951,1148,
%T 1162,1427,1532,1692,1861,2261,3760,4575,6974,7295,8367,8463,8600,
%U 14878,16165
%N Numbers k such that 2^(2*(k+1)) + 2^k - 1 is prime.
%e 2^4 + 2^1 + 1 = 19 is prime so a(1)=1.
%e 2^6 + 2^2 + 1 = 67 is prime so a(2)=2.
%e 2^8 + 2^3 + 1 = 263 is prime so a(3)=3.
%t a[n_]:=2^(2*(n+1))+2^n-1;lst={};Do[If[PrimeQ[a[n]],AppendTo[lst,n]],{n,0,7!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jan 03 2009 *)
%o (PARI) is(n)=ispseudoprime(2^(2*(n+1))+2^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%o (Magma) [k: k in [0..200] | IsPrime(2^(2*(k+1))+2^k-1)]; // _Jinyuan Wang_, Mar 20 2020
%Y Cf. A105182.
%K nonn,more
%O 1,2
%A _Pierre CAMI_, Apr 11 2005
%E More terms from _Ryan Propper_, Jan 31 2008
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