A103061 - OEIS

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A103061

Numbers n such that 7*10^n + 5*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 4, 18, 19, 646, 814, 5794, 16524, 19495, 26010, 29238 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (68*10^n-23)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 755...553.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(68*10^n - 23)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A081420 A039277 A045019 * A201880 A022384 A093022` `Adjacent sequences: A103058 A103059 A103060 * A103062 A103063 A103064`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005`
	EXTENSIONS	`a(8)-a(11) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010`

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Last modified February 15 17:13 EST 2012. Contains 205828 sequences.