A056684 - OEIS

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A056684

Numbers n such that 50*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

11, 12, 608 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (5*10^(n+1)-41)/9 is prime.`
	LINKS	`Index entries for primes involving repunits`
	MATHEMATICA	`Do[ If[ PrimeQ[50*(10^n - 1)/9 + 1], Print[n]], {n, 15000}]`
	CROSSREFS	`Sequence in context: A041262 A041607 A042097 * A042731 A087304 A121808` `Adjacent sequences: A056681 A056682 A056683 * A056685 A056686 A056687`
	KEYWORD	`hard,nonn,bref`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 10 2000`

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