cp's OEIS Frontend

A156982 Numbers k such that 2^k + 29 is prime.

%I A156982 #23 Sep 08 2022 08:45:41
%S A156982 1,3,5,7,9,13,15,17,23,27,33,37,43,63,69,73,79,89,117,127,239,395,409,
%T A156982 465,837,2543,10465,10837,17005,19285,24749,26473,29879,49197,56673,
%U A156982 67119,67689,71007,109393,156403,158757,181913,190945,207865,222943,419637
%N A156982 Numbers k such that 2^k + 29 is prime.
%C A156982 n cannot be of the form 4m+2 or 4m because 2^(2m+2) + 29 is divisible by 3 and 2^4m + 29 is divisible by 15. - Avik Roy (avik_3.1416(AT)yahoo.co.in), Feb 21 2009
%C A156982 a(47) > 5*10^5. - _Robert Price_, Oct 25 2015
%H A156982 Henri Lifchitz and Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=2^n%2B29&amp;action=Search">PRP Records, search for 2^n+29</a>
%e A156982 For k = 1, 2^1 + 29 = 31.
%e A156982 For k = 3, 2^3 + 29 = 37.
%t A156982 Delete[Union[Table[If[PrimeQ[2^n + 29], n, 0], {n, 1, 2600}]], 1]
%t A156982 Select[Range[500000], PrimeQ[2^#+29]&] (* _Robert Price_, Oct 04 2015 *)
%o A156982 (Magma) [n: n in [0..1000] | IsPrime(2^n+29)]; // _Vincenzo Librandi_, Oct 05 2015
%o A156982 (PARI) is(n)=ispseudoprime(2^n+29) \\ _Charles R Greathouse IV_, Jun 06 2017
%Y A156982 Cf. A019434 (Fermat primes 2^(2^n)+1).
%Y A156982 Cf. A057732, A059242, A057195, A057196, A102633, A102634, A057197, A057200, A057221, A057201, A057203, A157006, A157007, A247952, A247953, A220077.
%K A156982 nonn
%O A156982 1,2
%A A156982 Edwin Dyke (ed.dyke(AT)btinternet.com), Feb 20 2009
%E A156982 a(27)-a(38) from _Robert Price_, Oct 04 2015
%E A156982 a(39)-a(46) discovered by _Henri Lifchitz_ from Lifchitz link by _Robert Price_, Oct 04 2015