id:A102938 - OEIS Search Results

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

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1, 3, 4, 7, 12, 51, 87, 123, 198, 202, 537, 831, 1323, 2508, 2631, 5568, 6897, 7524, 9939 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (14*10^n+31)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 155...559.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(14*10^n + 31)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A049859 A124636 A049930 this_sequence A076784 A088764 A093124` `Adjacent sequences: A102935 A102936 A102937 this_sequence A102939 A102940 A102941`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 16 2004`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.