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Revision History for A282895

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newer changes | Showing entries 11-17

A282895

Numbers k such that (11*10^k + 91)/3 is prime.
(history; published version)

#7 by Michel Marcus at Fri Sep 28 00:20:38 EDT 2018

STATUS

proposed

reviewed

#6 by Robert Price at Thu Sep 27 22:55:45 EDT 2018

STATUS

editing

proposed

#5 by Robert Price at Thu Sep 27 22:55:36 EDT 2018

COMMENTS

a(24) > 2*10^5.

STATUS

approved

editing

#4 by Bruno Berselli at Fri Feb 24 10:31:42 EST 2017

STATUS

proposed

approved

#3 by Robert Price at Fri Feb 24 10:18:08 EST 2017

STATUS

editing

proposed

#2 by Robert Price at Fri Feb 24 10:17:49 EST 2017

NAME

allocated for Robert PriceNumbers k such that (11*10^k + 91)/3 is prime.

DATA

1, 2, 3, 4, 5, 7, 9, 15, 27, 29, 39, 62, 77, 106, 114, 357, 555, 962, 1013, 2372, 8235, 16047, 82323

OFFSET

1,2

COMMENTS

For k>1, numbers such that the digit 3 followed by k-2 occurrences of the digit 6 followed by the digits 97 is prime (see Example section).

a(24) > 10^5.

LINKS

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

Makoto Kamada, <a href="http://stdkmd.com/nrr/prime/primedifficulty.txt">Search for 36w97.</a>

EXAMPLE

3 is in this sequence because (11*10^3 + 91)/3 = 3697 is prime.

Initial terms and primes associated:

a(1) = 1, 67;

a(2) = 2, 397;

a(3) = 3, 3697;

a(4) = 4, 36697;

a(5) = 5, 366697; etc.

MATHEMATICA

Select[Range[0, 100000], PrimeQ[(11*10^# + 91)/3] &]

CROSSREFS

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

KEYWORD

allocated

nonn,more,hard,new

AUTHOR

Robert Price, Feb 24 2017

STATUS

approved

editing

#1 by Robert Price at Fri Feb 24 10:17:49 EST 2017

NAME

allocated for Robert Price

KEYWORD

allocated

STATUS

approved