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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; text; internal format)
OFFSET

1,2

COMMENTS

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

a(21) > 10^5. - Robert Price, Apr 19 2015

LINKS

Table of n, a(n) for n=1..20.

Makoto Kamada, Prime numbers of the form 144...449.

Index entries for primes involving repunits.

FORMULA

a(n) = A102017(n) + 1.

MATHEMATICA

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

CROSSREFS

Cf. A002275, A102017.

Sequence in context: A071069 A116439 A018525 * A287210 A236524 A295968

Adjacent sequences:  A102932 A102933 A102934 * A102936 A102937 A102938

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Dec 16 2004

EXTENSIONS

Addition of a(18)-a(20) from Kamada data by Robert Price, Dec 09 2010

STATUS

approved

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Last modified April 23 09:35 EDT 2019. Contains 322385 sequences. (Running on oeis4.)