The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A103048 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A103048

Numbers k such that 7*10^k - 9 is prime.
(history; published version)

#38 by Michel Marcus at Mon Jul 03 00:58:36 EDT 2023

STATUS

reviewed

approved

#37 by Joerg Arndt at Mon Jul 03 00:58:20 EDT 2023

STATUS

proposed

reviewed

#36 by Jon E. Schoenfield at Sun Jul 02 23:26:10 EDT 2023

STATUS

editing

proposed

#35 by Jon E. Schoenfield at Sun Jul 02 23:25:07 EDT 2023

COMMENTS

a(35) > 3*10^5. - Robert Price, Oct 14 2015Jul 02 2023

#34 by Jon E. Schoenfield at Sun Jul 02 23:24:46 EDT 2023

NAME

Numbers n k such that 7*10^nk - 9 is prime.

COMMENTS

Also numbers n k such that 6*10^n k + 9*R_n k - 8 is prime, where R_n k = 11...1 is the repunit (A002275) of length nk.

STATUS

proposed

editing

#33 by Robert Price at Sun Jul 02 23:16:02 EDT 2023

STATUS

editing

proposed

#32 by Robert Price at Sun Jul 02 23:15:40 EDT 2023

DATA

1, 2, 3, 4, 14, 15, 23, 28, 54, 100, 272, 373, 403, 568, 639, 842, 969, 1255, 1259, 3047, 4838, 6389, 12755, 15142, 34943, 37652, 38108, 38686, 39384, 43393, 47280, 55030, 161192, 226479

COMMENTS

a(3435) > 3*10^5. - Robert Price, Oct 14 2015

EXTENSIONS

a(34) from Robert Price, Jul 02 2023

STATUS

approved

editing

#31 by Charles R Greathouse IV at Thu Sep 08 08:45:16 EDT 2022

PROG

(MAGMAMagma) [n: n in [1..500] | IsPrime(7*10^n-9)]; // Vincenzo Librandi, Oct 15 2015

Discussion

Thu Sep 08

08:45

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

#30 by Charles R Greathouse IV at Thu Jan 17 13:44:07 EST 2019

LINKS

Makoto Kamada, <a href="httphttps://stdkmd.comnet/nrr/6/69991.htm#prime">Prime numbers of the form 699...991</a>.

Discussion

Thu Jan 17

13:44

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

#29 by Alois P. Heinz at Thu Oct 15 06:45:34 EDT 2015

STATUS

proposed

approved