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A108493 Integers n such that 10^n-57 is prime. 1
2, 7, 10, 11, 17, 19, 39, 49, 50, 61, 95, 106, 187, 196, 849, 889, 6436, 7370, 14446, 19647, 34399, 39922, 81297, 84305 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers corresponding to terms 849 and 889 are certified primes. (Primo 2.2.0 beta) - Ryan Propper, Jul 13 2005

No additional terms <100000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99943".

LINKS

Table of n, a(n) for n=1..24.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

EXAMPLE

n = 7 is a member because: 10^7-57 = 10000000-57 = 9999943, which is prime.

CROSSREFS

Cf. A089675, A095714, A092767, A108327, A108328, A108329, A108330, A108331, A108332, A177417.

Sequence in context: A045281 A050596 A045266 * A069494 A134712 A030344

Adjacent sequences:  A108490 A108491 A108492 * A108494 A108495 A108496

KEYWORD

more,nonn

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Jul 06 2005

EXTENSIONS

a(17)-a(19) from Kamada data by Robert Price, Dec 10 2010

a(20) from Kamada data by Robert Price, Dec 14 2010

a(21)-a(22) from Robert Price, Dec 15 2010

Edited by Ray Chandler, Dec 23 2010

a(23-24)=81297,84305 from Robert Price, May 29 2011

STATUS

approved

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Last modified September 26 05:09 EDT 2017. Contains 292502 sequences.