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A108316 Least k such that (k*n)^2 + k*n -1 and (k*n)^2 + k*n +1 are twin primes. 0
2, 1, 1, 2, 1, 1, 3, 1, 6, 2, 6, 2, 2, 27, 1, 11, 9, 3, 2, 1, 1, 3, 6, 1, 2, 1, 2, 20, 7, 24, 5, 9, 2, 107, 13, 8, 8, 1, 9, 14, 1, 9, 5, 4, 9, 3, 3, 6, 14, 1, 3, 12, 10, 1, 9, 10, 8, 5, 1, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..60.

EXAMPLE

(2*1)^2 + 2*1 -1 = 5, (2*1)^2 + 2*1 +1 = 7, 5 and 7 twin primes so k(1)=2

CROSSREFS

Sequence in context: A284315 A262928 A228429 * A322426 A145574 A182579

Adjacent sequences:  A108313 A108314 A108315 * A108317 A108318 A108319

KEYWORD

nonn

AUTHOR

Pierre CAMI, Jul 25 2005

STATUS

approved

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Last modified December 15 04:23 EST 2019. Contains 329991 sequences. (Running on oeis4.)