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A056805 Numbers n such that 6*10^n+1 is prime. +0
5
0, 1, 2, 8, 9, 15, 20, 26, 38, 45, 65, 112, 244, 303, 393, 560, 839, 1009, 1019, 1173, 1334, 2236, 2629, 4426, 8848, 20812, 37744 (list; graph; listen)
OFFSET

1,3

LINKS

Makoto Kamada, Factorizations of 600...001.

Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.

Index entries for primes involving repunits.

EXAMPLE

n=2 => (6*10^2+1)=601, which is prime.

MATHEMATICA

Do[ If[ PrimeQ[ 6*10^n + 1], Print[ n ]], {n, 0, 10000}]

CROSSREFS

Cf. A056716.

Sequence in context: A073606 A047353 A032928 this_sequence A046679 A004999 A105125

Adjacent sequences: A056802 A056803 A056804 this_sequence A056806 A056807 A056808

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 22 2000

EXTENSIONS

a(21) - a(24) from Hugo Pfoertner (hugo(AT)pfoertner.org), Feb 11 2004

20812 from Herman Jamke (hermanjamke(AT)fastmail.fm), Dec 27 2007

37744 from Jason Earls (zevi_35711(AT)yahoo.com), Mar 07 2008

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.


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