login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A297625 Primes of the form (2^(p^k) - 1)/(2^(p^(k - 1)) - 1), with p prime and k > 1. 0
5, 17, 73, 257, 65537, 262657, 4432676798593 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form Phi(x, 2), where x is a proper prime power and Phi is the cyclotomic polynomial.

Together with 3, supersequence of A019434.

Also called Mersenne-Fermat primes.

a(8) has 1031 digits and is too large to include.

REFERENCES

Fredrick Kennard, Unsolved Problems in Mathematics, Lulu Press, 2015, p. 160.

LINKS

Table of n, a(n) for n=1..7.

Wikipedia, Mersenne-Fermat primes

PROG

(MAGMA) lst:=[]; r:=7; pr:=PrimesUpTo(r); for k in [2..r] do for c in [1..#pr] do p:=pr[c]; if p^k le r^2 then MF:=Truncate((2^(p^k)-1)/(2^(p^(k-1))-1)); if IsPrime(MF) then Append(~lst, MF); end if; end if; end for; end for; Sort(lst);

CROSSREFS

Cf. A019434, A051156, A140797, A187823, A245730, A246547.

Sequence in context: A146577 A211405 A187823 * A084777 A149717 A149718

Adjacent sequences:  A297622 A297623 A297624 * A297626 A297627 A297628

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Jan 04 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 24 09:54 EDT 2019. Contains 322420 sequences. (Running on oeis4.)