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A051800 Numbers n such that 1 + double of product of first n primes is also a prime. 0
1, 2, 3, 4, 5, 11, 18, 23, 26, 30, 80, 120, 148, 220 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

5 is a member because 2*(2*3*5*7*11)+1=4621 is prime

CROSSREFS

2*A002110[n]+1 is prime. Cf. A051887, A051915.

Sequence in context: A181288 A255260 A052418 * A121432 A118968 A073528

Adjacent sequences:  A051797 A051798 A051799 * A051801 A051802 A051803

KEYWORD

nonn

AUTHOR

Labos Elemer, Dec 20 1999

STATUS

approved

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Last modified February 18 03:28 EST 2018. Contains 299298 sequences. (Running on oeis4.)