A102953 - OEIS

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A102953

Numbers n such that 2*10^n + 4*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 4, 7, 12, 30, 94, 178, 196, 564, 1801, 3520, 3538, 8233 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (22*10^n-13)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 244...443.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(22*10^n - 13)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A023624 A123194 A183336 * A111157 A169700 A162957` `Adjacent sequences: A102950 A102951 A102952 * A102954 A102955 A102956`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004`

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Last modified February 14 23:53 EST 2012. Contains 205689 sequences.