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%I #29 Jul 20 2019 08:07:01
%S 7,13,15,19,25,133,135,199,223,297,299,511,15263,16491,18967,32455
%N Numbers k such that k!! + 2^9 is prime.
%C a(17) > 50000. - _Robert Price_, Feb 15 2015
%H The OpenPFGW Project, <a href="http://www.primeform.net/openpfgw/">Primality Tester</a>
%t lst={};Do[If[PrimeQ[n!!+2^9], (*Print[n];*)AppendTo[lst, n]], {n, 6!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Aug 26 2008 *)
%t Select[Range[33000],PrimeQ[#!!+2^9]&] (* _Harvey P. Dale_, Mar 29 2019 *)
%Y Cf. A006882.
%Y Numbers k such that k!! + 2^s is prime: A080778 (s=0), A076185 (s=1), A076186 (s=2), A076188 (s=3), A076189 (s=4), A076190 (s=5), A076193 (s=6), A076194 (s=7), A076195 (s=8), A076197 (s=10).
%K nonn,more
%O 1,1
%A _Zak Seidov_, Nov 02 2002
%E Edited and extended (n < 4096) by _Hugo Pfoertner_, Jun 19 2003
%E a(13)-a(15) from _Robert Price_, Feb 25 2013
%E a(16) from _Robert Price_, Feb 15 2015