A103058 - OEIS

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A103058

Numbers n such that 7*10^n + 4*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 2, 19, 31, 106, 26194 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (67*10^n-13)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 744...443.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(67*10^n - 13)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A006962 A090819 A059697 * A161442 A135834 A106946` `Adjacent sequences: A103055 A103056 A103057 * A103059 A103060 A103061`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005`
	EXTENSIONS	`a(6) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010`

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Last modified February 17 23:58 EST 2012. Contains 206085 sequences.