A051899 - OEIS

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A051899

Smallest prime p such that (p-1)/(2n) is also a prime.

5, 13, 13, 17, 31, 37, 29, 113, 37, 41, 67, 73, 53, 197, 61, 97, 103, 73, 191, 281, 127, 89, 139, 97, 101, 157, 109, 113, 1103, 181, 311, 193, 199, 137, 211, 937, 149, 229, 157, 241, 1559, 421, 173, 617, 181, 277, 283, 193, 197, 701, 307, 313, 743, 541, 331 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	FORMULA	`(a[n]-1)/2n = A051686[n], the smallest 2k-Germain primes`
	EXAMPLE	`a[2]=13 because 13-1/4=3=A051686[2] and also a[3]=13, but because 13-1/6=2=A051686[3]` `a(8) = 113 as (113-1)/16 = 7 is a prime.`
	CROSSREFS	`Cf. A005385, A051686.` `Sequence in context: A116981 A094150 A130502 * A085956 A151994 A183782` `Adjacent sequences: A051896 A051897 A051898 * A051900 A051901 A051902`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Dec 16 1999`

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Last modified February 15 20:03 EST 2012. Contains 205852 sequences.