A102929 - OEIS

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A102929

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

1, 3, 9, 48, 58, 153, 261, 876, 1179, 1596, 17715 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (11*10^n+7)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 122...223.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(11*10^n + 7)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A018445 A129432 A111551 * A105458 A183952 A141051` `Adjacent sequences: A102926 A102927 A102928 * A102930 A102931 A102932`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2004`
	EXTENSIONS	`Addition of a(11) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010`

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Last modified February 16 20:10 EST 2012. Contains 205959 sequences.