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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A046867 Numbers n such that 10*11^n -1 is prime. 15
1, 3, 37, 119, 255, 355, 371, 497, 1759, 34863, 50719, 147709 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(13) > 2*10^5. - Robert Price, Jan 19 2015

REFERENCES

R. K. Guy, Unsolved Problems in Theory of Numbers, Section A3.

LINKS

Table of n, a(n) for n=1..12.

H. C. Williams, The primality of certain integers of the form 2Ar^n - 1, Acta Arith. 39 (1981), 7-17.

MATHEMATICA

Do[ If[ PrimeQ[10*11^n - 1], Print[n]], {n, 1, 2000}]

PROG

(PARI) is(n)=isprime(10*11^n-1) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A003307, A002235, A046865, A079906, A046866, A001771, A005541, A056725, A079907.

Sequence in context: A301358 A163156 A041067 * A154823 A109835 A066364

Adjacent sequences:  A046864 A046865 A046866 * A046868 A046869 A046870

KEYWORD

nonn,hard

AUTHOR

N. J. A. Sloane

EXTENSIONS

One more term from Robert G. Wilson v, Jan 16 2003

a(10)-a(12) from Robert Price, Jan 19 2015

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 October 19 13:01 EDT 2019. Contains 328222 sequences. (Running on oeis4.)