A201360 - OEIS

%I #13 May 13 2023 01:44:47

%S 1,2,39,44,62,1478,2306,35335

%N Numbers k such that (2^k - k + 1)*2^k + 1 is prime.

%e 2 is in the sequence because (2^2 - 2 + 1)*2^2 + 1 = 13 is prime.

%t lst={};Do[If[PrimeQ[(2^n - n+1)*2^n+1],AppendTo[lst,n]],{n,10000}];lst

%o (PARI) is(n)=ispseudoprime((2^n-n+1)<<n+1) \\ _Charles R Greathouse IV_, Feb 17 2017

%Y Cf. A201356, A201357, A201358, A201359, A201361, A201362, A201363.

%K nonn,hard,more

%O 1,2

%A _Michel Lagneau_, Nov 30 2011

%E a(8) from _Michael S. Branicky_, May 12 2023