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A111023 Integers n such that 9*10^n + 11 is a prime number. 0
1, 2, 3, 4, 6, 8, 16, 20, 27, 115, 180, 274, 576, 1111, 2404, 5127, 8082, 9514, 12808, 14752, 15926, 22670, 37432, 41988, 53707, 72595, 92742 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "90w11".

a(28) > 10^5. - Robert Price, Jan 28 2017

LINKS

Table of n, a(n) for n=1..27.

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

Index entries for primes involving repunits.

EXAMPLE

n = 6 is a member because 9*10^6 + 11 = 9*1000000 + 11 = 9000011, which is prime.

MATHEMATICA

Do[If[PrimeQ[9*10^n+11], Print[n]], {n, 1, 1300}] (* Zak Seidov, Sep 14 2006 *)

CROSSREFS

Cf. A100275 = numbers n such that 9*10^n-11 is prime.

Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054, A110980.

Sequence in context: A049708 A000031 A298072 * A261751 A294679 A008324

Adjacent sequences:  A111020 A111021 A111022 * A111024 A111025 A111026

KEYWORD

more,nonn

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

EXTENSIONS

Edited by N. J. A. Sloane, Apr 11 2008

a(16)-a(22) from Ray Chandler, Dec 23 2010

a(23)-a(27) from Robert Price, Jan 28 2017

STATUS

approved

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Last modified February 23 17:36 EST 2018. Contains 299584 sequences. (Running on oeis4.)