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A096774 Numbers n such that 9*10^n + 7 is prime. +0
3
1, 2, 3, 4, 5, 15, 19, 20, 46, 52, 53, 192, 380, 588, 776, 906, 1350, 1736, 2914, 7508, 15710, 16453, 17488, 18109 (list; graph; listen)
OFFSET

1,2

COMMENT

a(1) through a(12) have been certified prime. a(13) through a(19) are all Fermat and Lucas PRPs. No others less than 6300. - Jason Earls (zevi_35711(AT)yahoo.com), Aug 18 2004

LINKS

Makoto Kamada, Factorizations of 900...007.

Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.

Index entries for primes involving repunits.

EXAMPLE

n = 5; (9*10^5)+7 = 900007, which is prime.

MATHEMATICA

Do[ If[ PrimeQ[9*10^n + 7], Print[n]], {n, 0, 10000}] (from Robert G. Wilson v Jan 19 2005)

CROSSREFS

Sequence in context: A138986 A098552 A037340 this_sequence A102738 A098553 A132705

Adjacent sequences: A096771 A096772 A096773 this_sequence A096775 A096776 A096777

KEYWORD

more,nonn

AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Aug 16 2004

EXTENSIONS

More terms from Jason Earls (zevi_35711(AT)yahoo.com), Aug 18 2004

a(20) from Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

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Last modified July 23 17:35 EDT 2008. Contains 142285 sequences.


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