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A102935 Numbers n such that 10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 2
1, 2, 4, 11, 13, 26, 154, 196, 436, 529, 1111, 2563, 2641, 3233, 3883, 4256, 9298, 17293, 23270, 27197 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (13*10^n+41)/9 is prime.

LINKS

Makoto Kamada, Factorizations of 144...449.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(13*10^n + 41)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A071069 A116439 A018525 * A038193 A002382 A180384

Adjacent sequences:  A102932 A102933 A102934 * A102936 A102937 A102938

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2004

EXTENSIONS

Addition of a(18)-a(20) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 09 2010

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Last modified February 13 10:53 EST 2012. Contains 205459 sequences.