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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A102977 Numbers n such that 3*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
0, 2, 3, 5, 6, 20, 776, 1185, 3164, 4212, 10733, 21726, 38235 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (34*10^n+11)/9 is prime.

a(14) > 10^5. - Robert Price, May 08 2015

LINKS

Table of n, a(n) for n=1..13.

Makoto Kamada, Prime numbers of the form 377...779.

Index entries for primes involving repunits.

FORMULA

a(n) = A101843(n-1) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(34*10^n + 11)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101843.

Sequence in context: A109628 A192367 A227230 * A238335 A131599 A263650

Adjacent sequences:  A102974 A102975 A102976 * A102978 A102979 A102980

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 17 2004

EXTENSIONS

Addition of a(11)-a(12) from Kamada data by Robert Price, Dec 13 2010

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

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 November 24 07:53 EST 2020. Contains 338607 sequences. (Running on oeis4.)