A056698 - OEIS

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A056698

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

1, 15, 41, 83, 95, 341, 551, 669, 989, 1223, 6923 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,2`
	COMMENTS	`Also numbers n such that (4*10^n-1)/3 is prime.`
	LINKS	`Table of n, a(n) for n=1..11.` `Makoto Kamada, Factorizations of 133...33` `Index entries for primes involving repunits`
	MATHEMATICA	`Do[ If[ PrimeQ[ 10^n + 3*(10^n-1)/9], Print[n]], {n, 0, 30470}]`
	CROSSREFS	`Sequence in context: A219378 A103003 A024845 * A070007 A154267 A173351` `Adjacent sequences: A056695 A056696 A056697 * A056699 A056700 A056701`
	KEYWORD	`hard,nonn`
	AUTHOR	`Robert G. Wilson v, Aug 10 2000`
	STATUS	`approved`

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Last modified June 19 02:31 EDT 2013. Contains 226386 sequences.