A056689 - OEIS

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A056689

Numbers n such that 70*R_n + 3, where R_n = 11...1 is the repunit (A002275) of length n.

0, 1, 2, 4, 8, 11, 14, 20, 263, 382, 2719, 4493 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`Also numbers n such that (7*10^(n+1)-43)/9 is prime.`
	LINKS	`Index entries for primes involving repunits`
	MATHEMATICA	`Do[ If[ PrimeQ[70*(10^n - 1)/9 + 3], Print[n]], {n, 0, 5000}]`
	CROSSREFS	`Sequence in context: A078649 A161607 A022442 * A034037 A033153 A086790` `Adjacent sequences: A056686 A056687 A056688 * A056690 A056691 A056692`
	KEYWORD	`hard,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 10 2000`

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Last modified February 16 19:43 EST 2012. Contains 205949 sequences.