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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A102995 Numbers n such that 4*10^n + 7*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 22, 925, 2340, 15955, 16098, 55512, 82752 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (43*10^n-61)/9 is prime.

a(9) > 10^5. - Robert Price, Jun 01 2015

LINKS

Table of n, a(n) for n=1..8.

Makoto Kamada, Prime numbers of the form 477...771.

Index entries for primes involving repunits.

FORMULA

a(n) = A101732(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(43*10^n - 61)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101732.

Sequence in context: A095696 A322930 A200575 * A211887 A041927 A041924

Adjacent sequences:  A102992 A102993 A102994 * A102996 A102997 A102998

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 17 2005

EXTENSIONS

Two more PRP terms from Serge Batalov, Feb 15 2009

a(7)-a(8) from Robert Price, Jun 01 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 July 15 16:29 EDT 2019. Contains 325049 sequences. (Running on oeis4.)