The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A056694 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A056694

Numbers k such that 80*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
(history; published version)

#26 by Charles R Greathouse IV at Thu Sep 08 08:45:01 EDT 2022

PROG

(MAGMAMagma) [n: n in [0..500] | IsPrime((8*10^(n+1)-53) div 9)]; // Vincenzo Librandi, Nov 01 2014

Discussion

Thu Sep 08

08:45

OEIS Server: https://oeis.org/edit/global/2944

#25 by Joerg Arndt at Mon Jan 04 06:19:23 EST 2021

STATUS

reviewed

approved

#24 by Michel Marcus at Mon Jan 04 06:00:38 EST 2021

STATUS

proposed

reviewed

#23 by Georg Fischer at Mon Jan 04 05:56:52 EST 2021

STATUS

editing

proposed

#22 by Georg Fischer at Mon Jan 04 05:56:11 EST 2021

NAME

Numbers n k such that 80*R_n k + 3 is prime, where R_n k = 11...1 is the repunit (A002275) of length nk.

COMMENTS

Also numbers n k such that (8*10^(nk+1)-53)/9 is prime.

FORMULA

a(n) = A099422(n+1) - 1. [adapted by _Georg Fischer_, Jan 04 2021]

STATUS

approved

editing

Discussion

Mon Jan 04

05:56

Georg Fischer: A leading 0 was removed from A099422.

#21 by Charles R Greathouse IV at Thu Jan 17 13:44:05 EST 2019

LINKS

Makoto Kamada, <a href="httphttps://stdkmd.comnet/nrr/8/88883.htm#prime">Prime numbers of the form 88...883</a>.

Discussion

Thu Jan 17

13:44

OEIS Server: https://oeis.org/edit/global/2791

#20 by Ray Chandler at Thu May 21 19:21:37 EDT 2015

STATUS

editing

approved

#19 by Ray Chandler at Thu May 21 19:21:32 EDT 2015

CROSSREFS

Cf. A002275, A093166, A099422.

STATUS

approved

editing

#18 by Ray Chandler at Mon Apr 27 09:20:24 EDT 2015

STATUS

editing

approved

#17 by Ray Chandler at Mon Apr 27 09:20:20 EDT 2015

LINKS

Makoto Kamada, <a href="http://stdkmd.com/nrr/8/88883.htm#prime">Prime numbers of the form 88...883</a>.

Makoto Kamada, <a href="http://homepage2.nifty.com/m_kamada/math/88883.htm">Factorizations of 88...883</a>.

CROSSREFS

Cf. A002275, A099422.

STATUS

approved

editing