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A099411 Numbers n such that 3*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 0
1, 2, 3, 6, 46, 394, 978, 2586, 2811, 2968, 3642, 4827, 4918, 5592, 5706 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..15.

Index entries for primes involving repunits

MATHEMATICA

Do[ If[ PrimeQ[ 3(10^n - 1)/9 + 4], Print[n]], {n, 10000}]

CROSSREFS

Sequence in context: A127315 A018359 A049383 * A018372 A097350 A062309

Adjacent sequences:  A099408 A099409 A099410 * A099412 A099413 A099414

KEYWORD

hard,nonn

AUTHOR

Robert G. Wilson v, Oct 14 2004

STATUS

approved

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Last modified October 2 10:33 EDT 2014. Contains 247538 sequences.