A103053 - OEIS

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A103053

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

1, 4, 12, 13, 15, 36, 40, 90, 837, 2424, 2427, 2443, 15925, 16212 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (65*10^n+7)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 722...223.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(65*10^n + 7)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A051434 A074138 A120252 * A087760 A032498 A144613` `Adjacent sequences: A103050 A103051 A103052 * A103054 A103055 A103056`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005`
	EXTENSIONS	`a(13)-a(14) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010`

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Last modified February 14 13:08 EST 2012. Contains 205623 sequences.