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%I #9 Aug 02 2015 17:07:45
%S 1,3,5,7,9,13,15,31,33,47,65,99,103,147,197,203,257,399,411,471,497,
%T 979,1189,2851,3221,4689,5027,7131,7545,9049,9849
%N Numbers k that 4^k + 13^2 is prime.
%C See A178652.
%e 4^1 + 13^2 = 173 = prime(40), 1 is first term.
%e 4^3 + 13^2 = 233 = prime(51), 3 is 2nd term.
%e 4^5 + 13^2 = 1193 = prime(196), 5 is 3rd term.
%e 4^147 + 13^2 = 318286...15753 (89 digits), 147 is 14th term.
%e 4^197 + 13^2 = 403...9753 (119 digits), 197 is 15th term.
%t fQ[n_] := PrimeQ[(2^k)^2 + 169]; k = 1; lst = {}; While[k < 10^4, If[ fQ@k, AppendTo[lst, k]; Print@k]; k += 2]; lst (* _Robert G. Wilson v_, Jul 31 2010 *)
%o (PARI) forstep(k=1,999,2,if(ispseudoprime(4^n+169),print1(n", "))) \\ _Charles R Greathouse IV_, Aug 27 2013
%Y Cf. A176969, A176978, A177833, A178652.
%K nonn
%O 1,2
%A Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Jun 01 2010
%E a(16)-a(31) from _Robert G. Wilson v_, Jul 31 2010
%E New name from _Charles R Greathouse IV_, Aug 27 2013
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