A102978 - OEIS

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A102978

Numbers n such that 3*10^n + 8*R_n - 7 is a prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 3, 19, 30, 40, 42, 45, 70, 307, 538, 1609, 1668, 1674, 4492, 4935, 6112, 12819, 14079, 16020, 23005 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (35*10^n-71)/9 is a prime.`
	LINKS	`Makoto Kamada, Factorizations of 388...881.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(35*10^n - 71)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A062619 A180451 A108137 * A107165 A066811 A162307` `Adjacent sequences: A102975 A102976 A102977 * A102979 A102980 A102981`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004`
	EXTENSIONS	`Addition of a(17)-a(20) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 10 2010`

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Last modified February 15 23:34 EST 2012. Contains 205860 sequences.