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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A102992 Numbers n such that 4*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 3
1, 2, 4, 5, 13, 22, 25, 28, 38, 67, 142, 284, 295, 380, 397, 1217, 1640, 2885, 3286, 7735, 29306 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (41*10^n+13)/9 is prime.

a(22) > 10^5. - Robert Price, May 22 2015

LINKS

Table of n, a(n) for n=1..21.

Makoto Kamada, Prime numbers of the form 455...557.

Index entries for primes involving repunits.

FORMULA

a(n) = A101727(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(41*10^n + 13)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101727.

Sequence in context: A079407 A078652 A289491 * A273097 A232207 A136563

Adjacent sequences:  A102989 A102990 A102991 * A102993 A102994 A102995

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 17 2005

EXTENSIONS

Addition of a(21) from Kamada data by Robert Price, Dec 09 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 21 14:57 EDT 2018. Contains 316424 sequences. (Running on oeis4.)