A056694 - OEIS

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A056694

Numbers n such that 80*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 1, 2, 4, 7, 8, 14, 50, 70, 76, 223, 295, 314, 2089, 2905, 3394, 3881, 5113, 6055, 7253, 7994 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`Also numbers n such that (8*10^(n+1)-53)/9 is prime.`
	LINKS	`Index entries for primes involving repunits` `Makoto Kamada, Factorizations of 88...883.`
	MATHEMATICA	`Do[ If[ PrimeQ[80*(10^n - 1)/9 + 3], Print[n]], {n, 0, 5000}]`
	CROSSREFS	`Sequence in context: A018740 A018430 A018265 * A090606 A019539 A045594` `Adjacent sequences: A056691 A056692 A056693 * A056695 A056696 A056697`
	KEYWORD	`hard,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 10 2000`
	EXTENSIONS	`More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008`

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Last modified February 15 23:53 EST 2012. Contains 205860 sequences.