[seqfan] Re: 2^n + p = prime/composite

[Rick Shepherd]

...and here are the first thirty terms of a(n):
0,0,1,2,3,3,5,9,11,18,32,51,84,151,254,429,754,1311,2377,4199,7584,13785,24955,
45840,84002,153515,283659,524648,976217,1817659

(as calculated with PARI)

Rick



On Wed, Feb 24, 2010 at 11:32 AM, Ray Chandler
<rayjchandler at sbcglobal.net>wrote:

> I do not find either of them in the OEIS, but a(n)+b(n)= A007053(n).
> Ray
>
> >
> > Are either of these sequences already in the EIS, possibly
> > with a different (non-obviously identical) definition?
> >
> > a) a(n) = number of primes p, p <= 2^n, where 2^n + p is prime.
> > (Offset = 0).
> > 0,0,1,2,3,3,5,...
> >
> > b) b(n) = number of primes p, p <= 2^n, where 2^n + p is composite.
> > (Offset = 0).
> >
> > 0,1,1,2,3,8,13,...
> >
>
>
>
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