A102956 - OEIS

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A102956

Numbers n such that 2*10^n + 5*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 82, 322, 733, 2431, 8386, 15886, 19912 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (23*10^n+31)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 255...559.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(23*10^n + 31)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A092229 A048513 A116341 * A031696 A005972 A082972` `Adjacent sequences: A102953 A102954 A102955 * A102957 A102958 A102959`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004`
	EXTENSIONS	`Addition of a(7)-a(8) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010`

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Last modified February 17 04:58 EST 2012. Contains 205985 sequences.