id:A103013 - OEIS Search Results

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Numbers n such that 5*10^n + 4*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

+0
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2, 3, 86, 134, 185, 344, 396, 476, 834, 1799, 2147, 2418, 5216, 5882, 6216 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`Also numbers n such that (49*10^n-31)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 544...441.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(49*10^n - 31)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A042549 A153228 A041401 this_sequence A042901 A002983 A118167` `Adjacent sequences: A103010 A103011 A103012 this_sequence A103014 A103015 A103016`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 18 2005`

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Last modified November 21 21:21 EST 2009. Contains 167310 sequences.