id:A103019 - OEIS Search Results

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Numbers n such that 5*10^n + 7*R_n - 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

+0
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2, 6, 9, 27, 30, 48, 141, 150, 372, 422, 1097, 3570, 4607, 5289 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Also numbers n such that (52*10^n-61)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 577...771.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(52*10^n - 61)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A056879 A006746 A121624 this_sequence A101823 A093397 A082459` `Adjacent sequences: A103016 A103017 A103018 this_sequence A103020 A103021 A103022`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 18 2005`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.