The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A293280 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A293280

Numbers k such that (28*10^k - 31)/3 is prime.
(history; published version)

#14 by Michael De Vlieger at Sat Jun 08 15:58:59 EDT 2024

STATUS

proposed

approved

#13 by Jon E. Schoenfield at Sat Jun 08 15:52:24 EDT 2024

STATUS

editing

proposed

#12 by Jon E. Schoenfield at Sat Jun 08 15:52:14 EDT 2024

COMMENTS

For k > 1, numbers k such that the digit 9 followed by k-2 occurrences of the digit 3 followed by the digits 23 is prime (see Example section).

LINKS

Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficultyprime_difficulty.txt">Search for 93w23</a>.

EXAMPLE

Initial terms and primes associated primes:

STATUS

approved

editing

#11 by Joerg Arndt at Sun Dec 08 12:27:09 EST 2019

STATUS

reviewed

approved

#10 by Michel Marcus at Sun Dec 08 11:56:48 EST 2019

STATUS

proposed

reviewed

#9 by Robert Price at Sun Dec 08 11:08:16 EST 2019

STATUS

editing

proposed

#8 by Robert Price at Sun Dec 08 11:08:12 EST 2019

DATA

1, 3, 4, 13, 15, 24, 28, 48, 233, 558, 621, 1498, 1810, 2788, 3532, 3987, 4791, 7972, 12221, 13714, 15940, 41759, 46956, 47827, 51651, 102142

COMMENTS

a(2627) > 2*10^5.

LINKS

Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficulty.txt">Search for 93w23</a>.

EXTENSIONS

a(26) from Robert Price, Dec 08 2019

STATUS

approved

editing

#7 by Charles R Greathouse IV at Thu Jan 17 13:44:09 EST 2019

LINKS

Makoto Kamada, <a href="httphttps://stdkmd.comnet/nrr">Factorization of near-repdigit-related numbers</a>.

Makoto Kamada, <a href="httphttps://stdkmd.comnet/nrr/prime/primedifficulty.txt">Search for 93w23</a>

Discussion

Thu Jan 17

13:44

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

#6 by Susanna Cuyler at Thu Oct 05 09:48:44 EDT 2017

STATUS

proposed

approved

#5 by Jon E. Schoenfield at Wed Oct 04 20:45:27 EDT 2017

STATUS

editing

proposed