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A064220 Least k such that k*11^n +/- 1 are twin primes. 0
4, 18, 12, 12, 120, 168, 72, 78, 810, 312, 90, 138, 270, 948, 408, 192, 960, 1920, 738, 4698, 810, 1872, 6978, 2058, 3222, 570, 870, 390, 9708, 14118, 9378, 6822, 8730, 2250, 1008, 8052, 732, 5400, 2910, 5982, 2688, 16758, 1908, 258, 762, 1488, 12678 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..47.

MATHEMATICA

Do[ k = 1; While[ ! PrimeQ[ k*11^n + 1 ] || ! PrimeQ[ k*11^n - 1 ], k++ ]; Print[ k ], {n, 0, 50} ]

lk[n_]:=Module[{c=11^n, k=1}, While[!PrimeQ[k*c+1]||!PrimeQ[k*c-1], k++]; k]; Array[lk, 50, 0] (* Harvey P. Dale, Jun 15 2019 *)

CROSSREFS

Cf. A063983.

Sequence in context: A264003 A077109 A070923 * A205105 A231957 A275952

Adjacent sequences:  A064217 A064218 A064219 * A064221 A064222 A064223

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Sep 21 2001

STATUS

approved

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Last modified December 9 00:32 EST 2019. Contains 329871 sequences. (Running on oeis4.)