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A110559 Least j such that j*n^2 -1 and j*n^2 +1 are twin primes. 2
4, 1, 2, 12, 6, 2, 18, 3, 10, 6, 12, 3, 12, 18, 18, 57, 12, 5, 120, 12, 2, 3, 132, 2, 42, 3, 58, 45, 12, 7, 72, 15, 10, 3, 6, 2, 60, 30, 12, 3, 168, 2, 192, 18, 2, 33, 48, 10, 138, 39, 8, 63, 42, 22, 60, 42, 32, 3, 120, 6, 90, 18, 40, 165, 204, 7, 90, 18, 70, 6, 72, 27, 30, 15, 6, 18 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Define Sj=sum of j(n) for n=1 to N. Define Sn=sum of (2*log(n))^2 for n=1 to N. As N increases Sj/Sn tends to 0.6. - Pierre CAMI, Dec 13 2011

LINKS

Pierre CAMI, Table of n, a(n) for n = 1..10000

EXAMPLE

12*4*4-1=191, 191 and 193 are twin primes so j(4)=12.

CROSSREFS

Sequence in context: A024569 A206692 A159756 * A030441 A298570 A284771

Adjacent sequences:  A110556 A110557 A110558 * A110560 A110561 A110562

KEYWORD

nonn

AUTHOR

Pierre CAMI, Sep 12 2005

EXTENSIONS

Extended by Ray Chandler, Sep 15 2005

STATUS

approved

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Last modified February 16 03:36 EST 2019. Contains 320140 sequences. (Running on oeis4.)