A103067 - OEIS

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A103067

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

1, 4, 18, 28, 55, 1728, 1876, 1884, 6841, 10782, 25366, 98446, 137250 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (71*10^n+1)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 788...889.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(71*10^n + 1)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A099565 A063563 A166749 * A080519 A120407 A033166` `Adjacent sequences: A103064 A103065 A103066 * A103068 A103069 A103070`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005`
	EXTENSIONS	`a(10)-a(13) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010`

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Last modified February 15 02:50 EST 2012. Contains 205694 sequences.