A099415 - OEIS

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A099415

Numbers n such that 5*R_n - 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

12, 13, 609 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (5*10^n-41)/9 is prime.`
	LINKS	`Index entries for primes involving repunits`
	MATHEMATICA	`Do[ If[ PrimeQ[ 5(10^n - 1)/9 - 4], Print[n]], {n, 15000}]`
	CROSSREFS	`Sequence in context: A041309 A041310 A066321 * A042293 A061097 A121288` `Adjacent sequences: A099412 A099413 A099414 * A099416 A099417 A099418`
	KEYWORD	`nonn,bref`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2004`

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Last modified February 14 16:46 EST 2012. Contains 205635 sequences.