A103032 - OEIS

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A103032

Numbers n such that 6*10^n + 3*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 2, 4, 7, 18, 19, 23, 24, 34, 41, 56, 64, 84, 149, 272, 755, 1272, 2398, 2686, 4800, 5198, 6217, 8737, 12388, 12391, 19702 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (19*10^n-7)/3 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 633...331.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(19*10^n - 7)/3], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A027238 A076894 A047871 * A101569 A101805 A145777` `Adjacent sequences: A103029 A103030 A103031 * A103033 A103034 A103035`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 18 2005`
	EXTENSIONS	`Addition of a(24)-a(26) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 09 2010`

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Last modified February 14 13:08 EST 2012. Contains 205623 sequences.