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A102989 Numbers n such that 4*10^n + 3*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 3, 5, 6, 8, 15, 26, 53, 60, 97, 183, 205, 302, 396, 456, 467, 607, 828, 1860, 2743, 4273, 4781, 5712, 6038, 6637, 9222, 10832, 18865, 25848, 42247, 48547, 87565, 95588 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (13*10^n+11)/3 is prime.

a(34) > 10^5. - Robert Price, May 11 2015

LINKS

Table of n, a(n) for n=1..33.

Makoto Kamada, Prime numbers of the form 433...337.

Index entries for primes involving repunits.

FORMULA

a(n) = A101724(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(13*10^n + 11)/3], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101724.

Sequence in context: A039869 A076210 A039014 * A005623 A152989 A308051

Adjacent sequences:  A102986 A102987 A102988 * A102990 A102991 A102992

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 17 2005

EXTENSIONS

Addition of a(27)-a(29) from Kamada data by Robert Price, Dec 08 2010

a(30)-a(31) from Erik Branger, May 01 2013, submitted by Ray Chandler, Aug 16 2013

a(32)-a(33) from Robert Price, May 11 2015

STATUS

approved

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Last modified April 7 04:20 EDT 2020. Contains 333292 sequences. (Running on oeis4.)