A102954 - OEIS

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A102954

Numbers n such that 2*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

3, 9, 15, 21, 27, 87, 180, 1941, 3960, 4995, 8577, 23481, 27855 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (22*10^n+23)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 244...447.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(22*10^n + 23)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A016945 A110108 A162843 * A162486 A067201 A071526` `Adjacent sequences: A102951 A102952 A102953 * A102955 A102956 A102957`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004`
	EXTENSIONS	`Addition of a(12)-a(13) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 12 2010`

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Last modified February 14 00:47 EST 2012. Contains 205567 sequences.