A138599 - OEIS

%I #7 Apr 08 2018 16:04:18

%S 16,17,19,21,22,24,25,33,34,36,46,49,60,70,90,93,112,137,143,207,216,

%T 263,280,477,647,1257,1383

%N Numbers n such that 2^(2*n-31)-31 is prime.

%e 2^(2*19-31)-31=97, 2^(2*21-31)-31=2017, 2^(2*22-31)-31=8161, ...

%t q=31;For[i=q,i<=q,a={};Do[x=2^(2*n-i)-i;If[PrimeQ[x],AppendTo[a,n]],{n,20^2}];Print["2^(2*n-",i,")-",i," ",a];i=i+2]

%t Select[Range[1500],PrimeQ[2^(2#-31)-31]&]

%o (PARI) is(n)=isprime(2^(2*n-31)-31) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,easy

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 13 2008

%E More terms from _Harvey P. Dale_, Apr 08 2018