[seqfan] Re: Fermat's generalizations.

W. Edwin Clark wclark at mail.usf.edu
Sat Jan 2 18:08:23 CET 2016


if n = 4 then (2^n + 1 - n)/n  = 13/4 is not an integer so how can it be
prime.
if n = 5 then (2^n + 1 - n)/n =  28/5 is not an integer so you are not
talking about numerators.

Perhaps you mean  floor ( (2^n + 1 - n)/n)?


On Sat, Jan 2, 2016 at 4:17 AM, юрий герасимов <2stepan at rambler.ru> wrote:

>
> Dear SegFans, Fermat's generalizations are
>
> i  Numbers of form 2^n + 1 such that (2^n + 1 - n)/n is prime: 3, 9, 17,
> 33, 129, 257, 1025, 4194305, 274877906945,
> 309485009821345068724781057, 20282409603651670423947251286017,
> 22835963083295358096932575511191922182123945985,
> 50216813883093446110686315385661331328818843555712276103169,
> 205688069665150755269371147819668813122841983204197482918576129,
> 3369993333393829974333376885877453834204643052817571560137951281153
>
> ii Numbers n such that (2^n + 1 - n)/n Is prime: 1, 3, 4, 5, 7, 8, 10, 22,
> 38, 88, 104, 154, 195, 207, 221, 246, 349, 362, 427, 466, 519, (what in the
> next one?)
>
> iii Primes p such that (2^p + 1 - p)/p is prime:  3, 5, 7, 349. (what in
> the next one?)
>
> i or ii or iii is of general interest?
> for OEIS?
>
> Best regards. JSG
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>



More information about the SeqFan mailing list