A213677 Numbers n such that n and n + 12 are prime and there is a power of two in the interval (n, n+12).

5, 7, 11, 29, 31, 59, 61, 127, 251, 509, 1019, 1021, 262139, 1048571, 2147483647

Offset

1,1

Comments

It is a conjecture that this is a finite sequence. A search was conducted out to 2^1500.

Links

Table of n, a(n) for n=1..15.

Prog

(Magma)
//Program finds primes separated by an even number (called gap) which
//have a power of two between them. Program starts with the smallest
//power of two above gap. Primes less than this starting point can be
//checked by inspection.
gap:=12;
start:=Ilog2(gap)+1;
for i:= start to 1000 do
    powerof2:=2^i;
    for k:=powerof2-gap+1 to powerof2-1 by 2 do
        if (IsPrime(k) and IsPrime(k+gap)) then k;
        end if;
    end for;
end for;

Crossrefs

A046133, A221211.

Sequence in context: A106330 A057247 A157437 * A330775 A340750 A031134

Adjacent sequences: A213674 A213675 A213676 * A213678 A213679 A213680

Keyword

nonn

Author

Brad Clardy, Mar 04 2013

Status

approved