id:A057821 - OEIS Search Results

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Useful safe primes: a(n) = least nonnegative integer k such that 2^n - k is prime and (2^n-k-1)/2 is also prime.

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1, 5, 9, 5, 21, 29, 9, 5, 9, 17, 45, 161, 165, 269, 285, 17, 45, 233, 9, 17, 321, 317, 633, 677, 405, 437, 189, 1385, 69, 209, 9, 641, 849, 137, 45, 401, 381, 437, 1965, 2201, 741, 1493, 573, 857, 1485, 5297, 2709, 161, 465, 473, 1269, 4805, 789 (list; graph; listen)

	OFFSET	`3,2`
	CROSSREFS	`Cf. A013603.` `Sequence in context: A117014 A010720 A094389 this_sequence A133742 A134879 A051158` `Adjacent sequences: A057818 A057819 A057820 this_sequence A057822 A057823 A057824`
	KEYWORD	`nonn`
	AUTHOR	`Warren Smith (wds(AT)research.nj.nec.com), Nov 23 2000`

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Last modified December 2 11:54 EST 2009. Contains 167921 sequences.

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