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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A102937 Numbers n such that 10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 3
0, 1, 2, 5, 7, 19, 20, 28, 58, 250, 397, 7591, 32716, 70978, 83587 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Also numbers n such that (14*10^n+13)/9 is prime.

a(16) > 10^5. - Robert Price, Jan 17 2015

LINKS

Table of n, a(n) for n=1..15.

Makoto Kamada, Prime numbers of the form 155...557.

Index entries for primes involving repunits.

FORMULA

a(n) = A102020(n-1) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(14*10^n + 13)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A102020.

Sequence in context: A173929 A173299 A097052 * A045358 A128005 A045359

Adjacent sequences:  A102934 A102935 A102936 * A102938 A102939 A102940

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 16 2004

EXTENSIONS

0 added by Arkadiusz Wesolowski, Mar 10 2011

a(13) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

a(14)-a(15) from Robert Price, Jan 17 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 May 24 11:23 EDT 2019. Contains 323529 sequences. (Running on oeis4.)