A102707 - OEIS

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A102707

a(n)= least k such that k*(10^n) -1 or +1 is prime.

1, 1, 1, 2, 5, 2, 3, 2, 6, 6, 3, 11, 18, 4, 5, 6, 13, 11, 15, 3, 6, 14, 6, 6, 61, 8, 2, 2, 3, 9, 48, 48, 21, 15, 6, 30, 3, 9, 6, 18, 6, 33, 30, 3, 60, 6, 24, 33, 33, 8, 71, 31, 11, 2, 5, 3, 24, 9, 16, 39, 19, 6, 9, 53, 60, 6, 26, 3, 16, 23, 17, 19, 44, 6, 131, 56, 8, 26, 9, 42, 12, 3, 24, 41 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,4`
	LINKS	`Pierre CAMI, Table of n,a(n) for n=1,...,999`
	EXAMPLE	`for n=0 1(10^0)+1=2 prime so a(0)=1` `for n=1 1(10^1)+1=11 prime so a(1)=1` `for n=2 1(10^2)+1=101 prime so a(2)=1` `for n=3 2(10^3)-1=1999 prime so a(3)=2`
	CROSSREFS	`Sequence in context: A065267 A100955 A049413 * A134486 A088006 A078311` `Adjacent sequences: A102704 A102705 A102706 * A102708 A102709 A102710`
	KEYWORD	`nonn`
	AUTHOR	`Pierre CAMI (pierre-cami(AT)bbox.fr), Feb 05 2005`
	EXTENSIONS	`Initial term of b-file corrected by N. J. A. Sloane, Aug 31 2009`

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Last modified February 17 23:32 EST 2012. Contains 206085 sequences.