A099422 - OEIS

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A099422

Numbers n such that 8*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 1, 2, 3, 5, 8, 9, 15, 51, 71, 77, 224, 296, 315, 2090, 2906, 3395, 3882, 5114, 6056, 7254, 7995 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`Also numbers n such that (8*10^n-53)/9 is prime.`
	LINKS	`Index entries for primes involving repunits` `Makoto Kamada, Factorizations of 88...883.`
	FORMULA	`Equals A056694 + 1 - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008`
	MATHEMATICA	`Do[ If[ PrimeQ[ 8(10^n - 1)/9 - 5], Print[n]], {n, 0, 5000}]`
	CROSSREFS	`Sequence in context: A141399 A104737 A120057 * A056903 A028770 A028800` `Adjacent sequences: A099419 A099420 A099421 * A099423 A099424 A099425`
	KEYWORD	`nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 14 2004`
	EXTENSIONS	`More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008`

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Last modified February 17 16:49 EST 2012. Contains 206058 sequences.