A102972 - OEIS

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A102972

Numbers n such that 3*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 1, 3, 6, 12, 33, 69, 111, 1965, 5646, 7404, 11103, 20790, 24840 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`Also numbers n such that (32*10^n+13)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 355...557.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(32*10^n+13)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A026079 A066710 A033648 * A075209 A075207 A136121` `Adjacent sequences: A102969 A102970 A102971 * A102973 A102974 A102975`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004`
	EXTENSIONS	`Addition of a(12)-a(14) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010`

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Last modified February 17 10:05 EST 2012. Contains 206009 sequences.