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A102951 Numbers n such that 2*10^n + 3*R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 2
1, 2, 3, 4, 8, 11, 13, 24, 28, 52, 54, 94, 297, 657, 1006, 5347, 8189, 9314, 23055, 53287, 64807 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (7*10^n+17)/3 is prime.

a(22) > 10^5. - Robert Price, Nov 25 2014

LINKS

Table of n, a(n) for n=1..21.

Makoto Kamada, Prime numbers of the form 233...339.

Index entries for primes involving repunits.

FORMULA

a(n) = A101956(n) + 1. - Robert Price, Nov 25 2014

MATHEMATICA

Do[ If[ PrimeQ[(7*10^n + 17)/3], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101956.

Sequence in context: A279194 A050727 A295323 * A015935 A135909 A046812

Adjacent sequences:  A102948 A102949 A102950 * A102952 A102953 A102954

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 17 2004

EXTENSIONS

Addition of a(19) from Kamada data by Robert Price, Dec 10 2010

a(20)-a(21) from Kamada data by Robert Price, Nov 25 2014

STATUS

approved

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Last modified March 19 11:10 EDT 2019. Contains 321329 sequences. (Running on oeis4.)