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A103108 Numbers n such that 9*10^n + 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
2, 3, 32, 42, 75, 368, 1392, 16350, 49101, 49689, 91839 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that (89*10^n-53)/9 is prime.

a(12) > 10^5. - Robert Price, Nov 12 2015

LINKS

Table of n, a(n) for n=1..11.

Makoto Kamada, Prime numbers of the form 988...883.

Index entries for primes involving repunits.

FORMULA

a(n) = A101017(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(89*10^n - 53)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101017.

Sequence in context: A176894 A041053 A212763 * A107124 A141049 A052830

Adjacent sequences:  A103105 A103106 A103107 * A103109 A103110 A103111

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 19 2005

EXTENSIONS

a(8) from Kamada data by Robert Price, Dec 14 2010

a(9)-a(10) from Erik Branger May 01 2013 by Ray Chandler, Aug 17 2013

a(11) from Robert Price, Nov 12 2015

STATUS

approved

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Last modified June 20 21:35 EDT 2021. Contains 345255 sequences. (Running on oeis4.)