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A103077 Numbers n such that 8*10^n + 2*R_n + 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 2, 5, 8, 14, 55, 103, 331, 1067, 13711, 24397, 54583 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (74*10^n+61)/9 is prime.

a(13) > 10^5. - Robert Price, Oct 26 2015

LINKS

Table of n, a(n) for n=1..12.

Makoto Kamada, Prime numbers of the form 822...229.

Index entries for primes involving repunits.

FORMULA

a(n) = A101064(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(74*10^n + 61)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101064.

Sequence in context: A263235 A017988 A282444 * A090980 A329603 A309546

Adjacent sequences:  A103074 A103075 A103076 * A103078 A103079 A103080

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 19 2005

EXTENSIONS

a(10)-a(11) from Kamada data by Robert Price, Dec 14 2010

a(12) from Robert Price, Oct 26 2015

STATUS

approved

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Last modified July 28 19:33 EDT 2021. Contains 346335 sequences. (Running on oeis4.)