A102981 - OEIS

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A102981

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

1, 4, 5, 13, 31, 55, 58, 59, 61, 79, 91, 103, 121, 196, 229, 9439, 13051, 22960 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (37*10^n+17)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 411...113.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(37*10^n + 17)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A147001 A140683 A071341 * A029663 A082312 A195747` `Adjacent sequences: A102978 A102979 A102980 * A102982 A102983 A102984`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 21 2004`
	EXTENSIONS	`Addition of a(17)-a(18) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 10 2010`

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Last modified February 16 01:56 EST 2012. Contains 205860 sequences.