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%I #15 Sep 08 2022 08:45:38
%S 17,73,521,262153,1073741833,144115188075855881,73786976294838206473,
%T 273406340597876490546562778389702670669146178861651554553221325801244124899921990402939147127881737
%N Primes of the form 8^k + 9.
%C 8^k + 9 is prime for k = 1, 2, 3, 6, 10, 19, 22, ...
%H Vincenzo Librandi, <a href="/A145440/b145440.txt">Table of n, a(n) for n = 1..9</a>
%e For k=1, 8^1 + 9 = 17;
%e for n=2, 8^2 + 9 = 73;
%e for n=3, 8^3 + 9 = 521.
%t Select[8^Range[120]+9,PrimeQ] (* _Harvey P. Dale_, Jan 18 2011 *)
%o (Magma) [a: n in [0..200] | IsPrime(a) where a is 8^n+9];
%Y A subsequence of A104070. Cf. A057196.
%K nonn
%O 1,1
%A _Vincenzo Librandi_, Mar 11 2009