A103085 - OEIS

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A103085

Numbers n such that 8*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

2, 8, 1056, 19835, 20018, 36464 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	COMMENTS	`Also numbers n such that (77*10^n+13)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 855...557.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(77*10^n + 13)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A004491 A132573 A061591 * A084148 A014115 A014116` `Adjacent sequences: A103082 A103083 A103084 * A103086 A103087 A103088`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005`
	EXTENSIONS	`a(4)-a(6) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010`

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Last modified February 16 12:15 EST 2012. Contains 205909 sequences.