A102987 - OEIS

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A102987

Numbers n such that 4*10^n + 2*R_n + 7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 3, 2043, 5967, 39855 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (38*10^n+61)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 422...229.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(38*10^n + 61)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A096730 A193149 A024047 * A004814 A203497 A145700` `Adjacent sequences: A102984 A102985 A102986 * A102988 A102989 A102990`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`
	EXTENSIONS	`Addition of a(5) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010`

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Last modified February 14 08:32 EST 2012. Contains 205614 sequences.