A056722 - OEIS

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A056722

Numbers n such that 8*10^n + R_n is prime, where R_n = 11...1 is the repunit (A002275) of length n.

2, 3, 26, 110, 141, 474, 902, 1746, 2997, 3627, 3788 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (73*10^n-1)/9 is prime.` `The next term is > 10000. - Hugo Pfoertner (hugo(AT)pfoertner.org), Oct 21 2004`
	LINKS	`Makoto Kamada, Factorizations of 811...11` `Index entries for primes involving repunits`
	MATHEMATICA	`Do[ If[ PrimeQ[ 8*10^n + (10^n-1)/9], Print[n]], {n, 0, 5000}]`
	CROSSREFS	`Sequence in context: A041659 A042043 A178196 * A181225 A143876 A184506` `Adjacent sequences: A056719 A056720 A056721 * A056723 A056724 A056725`
	KEYWORD	`hard,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 11 2000`

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Last modified February 15 05:45 EST 2012. Contains 205694 sequences.