A102930 - OEIS

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A102930

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

1, 2, 4, 14, 25, 32, 56, 62, 811, 812, 1084, 2533, 11924 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (11*10^n+43)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 122...227.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(11*10^n + 43)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A074716 A090889 A096012 * A135113 A050564 A047830` `Adjacent sequences: A102927 A102928 A102929 * A102931 A102932 A102933`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2004`
	EXTENSIONS	`Addition of a(13) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 12 2010`

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Last modified February 16 08:13 EST 2012. Contains 205893 sequences.