login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A103051 Numbers n such that 7*10^n + R_n + 8 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 2, 4, 17, 25, 32, 50, 74, 173, 1724, 2084, 11398 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (64*10^n+71)/9 is prime.

a(13) > 10^5. - Robert Price, Sep 21 2015

LINKS

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

Makoto Kamada, Prime numbers of the form 711...119.

Index entries for primes involving repunits.

FORMULA

a(n) = A101132(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(64*10^n + 71)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101132.

Sequence in context: A006276 A318367 A317488 * A095018 A081356 A018269

Adjacent sequences:  A103048 A103049 A103050 * A103052 A103053 A103054

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 19 2005

EXTENSIONS

a(12) 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 | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 26 11:48 EDT 2020. Contains 337371 sequences. (Running on oeis4.)