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A102934 Numbers n such that 10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 3, 4, 6, 9, 22, 28, 34, 37, 61, 82, 274, 276, 735, 1443, 2215, 2968, 3301, 3883, 3991, 5152, 8032, 8946, 46642, 57691 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (13*10^n+23)/9 is prime.

a(26) > 10^5. - Robert Price, Feb 19 2015

LINKS

Table of n, a(n) for n=1..25.

Makoto Kamada, Prime numbers of the form 144...447.

Index entries for primes involving repunits.

FORMULA

a(n) = A102016(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(13*10^n + 23)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A102016.

Sequence in context: A301657 A241342 A018830 * A191699 A293272 A192286

Adjacent sequences:  A102931 A102932 A102933 * A102935 A102936 A102937

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 16 2004

EXTENSIONS

a(24) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

a(25) from Robert Price, Feb 19 2015

STATUS

approved

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Last modified April 24 18:03 EDT 2019. Contains 322430 sequences. (Running on oeis4.)