A138600 - OEIS

%I #4 Jun 13 2017 12:56:52

%S 17,21,31,55,85,91,121,159,175,379,555,769

%N Numbers n such that 2^(2*n-33)-33 is prime.

%e 2^(2*21-33)-33=479, 2^(2*31-33)-33=536870879, 2^(2*55-33)-33=151115727451828646838239, ...

%t q=33;For[i=q,i<=q,a={};Do[x=2^(2*n-i)-i;If[PrimeQ[x],AppendTo[a,n]],{n,10^3}];Print["2^(2*n-",i,")-",i," ",a];i=i+2]

%o (PARI) is(n)=isprime(2^(2*n-33)-33) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,easy

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 13 2008