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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 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Makoto Kamada, Factorizations of 233...339.

Index entries for primes involving repunits.

MATHEMATICA

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

CROSSREFS

Sequence in context: A114854 A127279 A050727 * A015935 A135909 A046812

Adjacent sequences:  A102948 A102949 A102950 * A102952 A102953 A102954

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004

EXTENSIONS

Addition of a(19) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 10 2010

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Last modified February 16 12:14 EST 2012. Contains 205908 sequences.