id:A102994 - OEIS Search Results

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Numbers n such that 4*10^n + 6*R_n - 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

+0
4

1, 2, 7, 9, 14, 24, 45, 49, 73, 74, 232, 338, 397, 504, 1063, 2817, 5305 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Also numbers n such that (14*10^n-17)/3 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 466...661.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(14*10^n - 17)/3], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A077470 A047352 A074244 this_sequence A085544 A106352 A098017` `Adjacent sequences: A102991 A102992 A102993 this_sequence A102995 A102996 A102997`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.