A102986 - OEIS

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A102986

Numbers n such that 4*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 4, 136, 181, 325, 3292, 3871, 4690, 7876, 11911, 16096, 21649 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (38*10^n+43)/9 is prime.`
	LINKS	`Makoto Kamada, Factorizations of 422...227.` `Index entries for primes involving repunits.`
	MATHEMATICA	`Do[ If[ PrimeQ[(38*10^n + 43)/9], Print[n]], {n, 0, 10000}]`
	CROSSREFS	`Sequence in context: A045482 A006429 A016483 * A012160 A012197 A202299` `Adjacent sequences: A102983 A102984 A102985 * A102987 A102988 A102989`
	KEYWORD	`more,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 17 2005`
	EXTENSIONS	`Addition of a(10)-a(12) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 13 2010`

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Last modified February 15 15:20 EST 2012. Contains 205823 sequences.