A099414 - OEIS

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A099414

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

0, 3, 5, 6, 48, 108, 245, 1044 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (4*10^n+41)/9 is prime.`
	LINKS	`Index entries for primes involving repunits`
	MATHEMATICA	`Do[ If[ PrimeQ[ 4(10^n - 1)/9 + 5], Print[n]], {n, 5000}]`
	CROSSREFS	`Sequence in context: A103022 A086189 A137082 * A004785 A099744 A024601` `Adjacent sequences: A099411 A099412 A099413 * A099415 A099416 A099417`
	KEYWORD	`nonn,more`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2004`

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Last modified February 16 13:47 EST 2012. Contains 205919 sequences.