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A099005 Numbers n such that 4*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 2
1, 2, 3, 4, 6, 7, 8, 12, 23, 59, 75, 144, 204, 268, 760, 1216, 1430, 1506, 1509, 2804, 2924, 3201, 3305, 5753, 9268, 11279, 19677, 23414, 28627, 31362, 42299, 49119, 63747, 81767 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (14*10^n-11)/3 is a prime number.

a(35) > 10^5. - Robert Price, Mar 30 2015

LINKS

Table of n, a(n) for n=1..34.

Makoto Kamada, Prime numbers of the form 466...663.

Index entries for primes involving repunits.

FORMULA

a(n) = A101730(n) + 1.

EXAMPLE

For n = 1, 2, 3, 4, 6, 7, 8 are members since 43, 463, 4663, 46663, 4666663, 46666663 and 466666663 are primes.

MATHEMATICA

Do[ If[ PrimeQ[(14*10^n - 11)/3], Print[n]], {n, 0, 10000}] (* Robert G. Wilson v, Dec 17 2004 *)

CROSSREFS

Cf. A101730.

Sequence in context: A070525 A283112 A174099 * A336739 A257648 A096360

Adjacent sequences:  A099002 A099003 A099004 * A099006 A099007 A099008

KEYWORD

more,nonn

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Nov 07 2004

EXTENSIONS

a(15) - a(21) from Robert G. Wilson v, Dec 22 2004

a(22) - a(25) from Robert G. Wilson v, Jan 17 2005

a(26)-a(27) from Kamada link by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(28)-a(29) from Kamada data by Robert Price, Dec 08 2010

a(30)-a(32) from Erik Branger, May 01 2013, submitted by Ray Chandler, Aug 16 2013

a(33)-a(34) from Kamada data by Robert Price, Mar 30 2015

STATUS

approved

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Last modified March 1 03:32 EST 2021. Contains 341732 sequences. (Running on oeis4.)