A056654 - OEIS

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A056654

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

0, 1, 2, 4, 8, 10, 23, 83, 220, 1313, 2951 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	COMMENTS	`Also numbers n such that (10^(n+1)+17)/9 is prime.`
	LINKS	`Index entries for primes involving repunits`
	MATHEMATICA	`Do[ m = n; If[ primeQ[ 10*(10^n - 1)/9 + 3 ], Print[ n ] ], {n, 1, 1350} ]`
	CROSSREFS	`Cf. A093011 (corresponding primes).` `Sequence in context: A004655 A127101 A124849 * A020950 A056386 A116636` `Adjacent sequences: A056651 A056652 A056653 * A056655 A056656 A056657`
	KEYWORD	`hard,nonn`
	AUTHOR	`Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 09 2000`
	EXTENSIONS	`a(10) (only a probable prime) from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Mar 14 2004`

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Last modified February 17 09:17 EST 2012. Contains 206009 sequences.