A103030 - OEIS

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A103030

Numbers n such that 6*10^n + 2*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 3, 7, 16, 39, 229, 352, 433, 766, 2887, 2976, 10836, 15097 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (56*10^n-11)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 622...221.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(56*10^n - 11)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A014140 A103439 A147321 * A001698 A029761 A009337` `Adjacent sequences: A103027 A103028 A103029 * A103031 A103032 A103033`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 18 2005`
	EXTENSIONS	`Addition of a(12)-a(13) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010`

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Last modified February 17 06:27 EST 2012. Contains 205998 sequences.