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A051686 Smallest prime p such that 2n*p+1 is also prime. 8
2, 3, 2, 2, 3, 3, 2, 7, 2, 2, 3, 3, 2, 7, 2, 3, 3, 2, 5, 7, 3, 2, 3, 2, 2, 3, 2, 2, 19, 3, 5, 3, 3, 2, 3, 13, 2, 3, 2, 3, 19, 5, 2, 7, 2, 3, 3, 2, 2, 7, 3, 3, 7, 5, 3, 3, 2, 2, 7, 2, 3, 3, 3, 2, 7, 3, 2, 3, 2, 2, 13, 3, 2, 37, 5, 3, 3, 2, 2, 13, 3, 5, 3, 2, 11, 13, 2, 2, 31, 3, 3, 7, 2, 5, 3, 3, 2, 7, 2, 2 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

EXAMPLE

a(29)=19 because 19 is the smallest prime p such that 2*29*p+1 is prime.

CROSSREFS

Cf. A005384, A051644-A051654. These are the primes arising in A051899.

Sequence in context: A116909 A085239 A126014 * A079294 A076733 A079643

Adjacent sequences:  A051683 A051684 A051685 * A051687 A051688 A051689

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu)

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Last modified February 17 00:09 EST 2012. Contains 205978 sequences.