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A177866 Numbers n such that 10^n - 69 is prime. 1
2, 4, 6, 7, 8, 14, 20, 110, 138, 140, 145, 300, 390, 1484, 3194, 3300, 3950, 4986, 5574, 5630, 5874, 8866, 11390, 45130, 86110 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The next term, if it exists, is > 100000.

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "99931".

LINKS

Table of n, a(n) for n = 1..25

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

Index entries for primes involving repunits.

EXAMPLE

10^6 - 69 = 999931 which is a prime number.

MATHEMATICA

m=1000; For[n=1, n<m, If[PrimeQ[10^n-69], Print[n]]; n++ ]

PROG

(PARI) is(n)=ispseudoprime(10^n-69) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A108330, A108328.

Sequence in context: A015924 A096750 A088458 * A065853 A048284 A026516

Adjacent sequences:  A177863 A177864 A177865 * A177867 A177868 A177869

KEYWORD

more,nonn

AUTHOR

Robert Price, Dec 28 2010

EXTENSIONS

a(24-25)=45130,86110 from Robert Price, May 29 2011

STATUS

approved

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