The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A285553 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A285553

Numbers k such that (43*10^k - 403)/9 is prime.
(history; published version)

#53 by Michael De Vlieger at Sat May 25 19:35:07 EDT 2024

STATUS

proposed

approved

#52 by Jon E. Schoenfield at Sat May 25 18:47:38 EDT 2024

STATUS

editing

proposed

#51 by Jon E. Schoenfield at Sat May 25 18:47:36 EDT 2024

COMMENTS

For k > 1, numbers k such that the digit 4 followed by k-2 occurrences of the digit 7 followed by the digits 33 is prime (see Example section).

LINKS

Makoto Kamada, <a href="https://stdkmd.net/nrr/prime/primedifficultyprime_difficulty.txt">Search for 47w33.</a>.

EXAMPLE

Initial terms and primes associated primes:

STATUS

approved

editing

#50 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 47w33.</a>

Discussion

Thu Jan 17

13:44

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

#49 by Joerg Arndt at Sat Jan 05 04:41:37 EST 2019

STATUS

reviewed

approved

#48 by Michel Marcus at Sat Jan 05 01:51:07 EST 2019

STATUS

proposed

reviewed

#47 by Muniru A Asiru at Sat Jan 05 01:23:10 EST 2019

STATUS

editing

proposed

#46 by Muniru A Asiru at Sat Jan 05 01:23:05 EST 2019

MAPLE

select(k->isprime((43*10^k-403)/9), [$1..1000]); # Muniru A Asiru, Jan 05 2019

STATUS

proposed

editing

#45 by Robert Price at Fri Jan 04 22:40:51 EST 2019

STATUS

editing

proposed

#44 by Robert Price at Fri Jan 04 22:40:42 EST 2019

DATA

1, 2, 3, 6, 11, 20, 23, 24, 26, 36, 56, 224, 411, 543, 611, 1541, 1632, 3719, 3888, 4917, 11454, 24275, 51816, 58563, 119024

COMMENTS

a(2526) > 2*10^5.

EXTENSIONS

a(25) from Robert Price, Jan 04 2019

STATUS

approved

editing