login
Primes of the form 2^k - k^2.
9

%I #29 Feb 18 2025 21:52:52

%S 7,79,431,130783,523927,2251799813682647,9007199254738183,

%T 2417851639229258349405791,9671406556917033397642519,

%U 664613997892457936451903530140158127,784637716923335095479473677900958302012794430558004278391

%N Primes of the form 2^k - k^2.

%H Vincenzo Librandi, <a href="/A075896/b075896.txt">Table of n, a(n) for n = 1..20</a>

%F a(n) = A024012(A072180(n)). - _Elmo R. Oliveira_, Feb 18 2025

%t Select[Table[2^n - n^2, {n, 500}], PrimeQ] (* _Vincenzo Librandi_, Dec 07 2011 *)

%o (PARI) for(n=2,10^7,if(isprime(2^n-n^2),print1(2^n-n^2",")))

%o (Magma) [a: n in [1..200] | IsPrime(a) where a is 2^n-n^2]; // _Vincenzo Librandi_, Dec 07 2011

%Y Primes in A024012.

%Y Cf. A061119, A072180.

%K nonn,easy,changed

%O 1,1

%A _Zak Seidov_, Oct 17 2002

%E More terms from _Ralf Stephan_, Mar 30 2003