id:A103017 - OEIS Search Results

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Numbers n such that 5*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

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1, 2, 4, 7, 22, 28, 36, 109, 155, 868, 1777, 2465, 3874, 4506, 4684, 5503 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (17*10^n-11)/3 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 566...663.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(17*10^n - 11)/3], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A145777 A153550 A102984 this_sequence A091833 A026080 A071795` `Adjacent sequences: A103014 A103015 A103016 this_sequence A103018 A103019 A103020`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 18 2005`

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Last modified December 20 00:58 EST 2009. Contains 171054 sequences.