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A064217 Least k such that k*7^n +/- 1 are twin primes. 3
4, 6, 18, 24, 138, 60, 150, 720, 150, 234, 138, 966, 138, 420, 60, 1584, 420, 60, 1830, 1134, 162, 1080, 1482, 684, 240, 10074, 3378, 3300, 2742, 984, 2400, 4050, 5262, 3510, 3378, 960, 3612, 516, 6840, 6474, 4680, 4950, 12612, 7986, 4290, 8046, 5208 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..46.

MATHEMATICA

Do[ k = 1; While[ ! PrimeQ[ k*7^n + 1 ] || ! PrimeQ[ k*7^n - 1 ], k++ ]; Print[ k ], {n, 0, 50} ]

CROSSREFS

Cf. A063983, A064213, A064214, A064215, A064218, A064220, A064221.

Sequence in context: A219190 A337617 A120391 * A026623 A026689 A138276

Adjacent sequences:  A064214 A064215 A064216 * A064218 A064219 A064220

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Sep 21 2001

EXTENSIONS

Offset corrected by Georg Fischer, May 01 2022

STATUS

approved

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Last modified May 16 17:26 EDT 2022. Contains 353718 sequences. (Running on oeis4.)