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

 

Logo

Many excellent designs for a new banner were submitted. We will use the best of them in rotation.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A103094 Numbers n such that 9*10^n + 2*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
5, 29, 60, 147, 186, 456, 678, 1373, 3378, 15726 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that (83*10^n+7)/9 is prime.

LINKS

Table of n, a(n) for n=1..10.

Makoto Kamada, Factorizations of 922...223.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(83*10^n + 7)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A177831 A115706 A031394 * A108928 A097812 A176333

Adjacent sequences:  A103091 A103092 A103093 * A103095 A103096 A103097

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 19 2005

EXTENSIONS

a(10) from Kamada data by Robert Price, Dec 14 2010

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified April 19 05:22 EDT 2014. Contains 240738 sequences.