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 A098873 Least k such that 2*((6*n)^k) - 1 is prime. 0
 1, 1, 2, 1, 1, 1, 1, 4, 1, 5, 1, 34, 7, 1, 1, 1, 2, 2, 1, 1, 1, 1, 4, 24, 8, 1, 10, 7, 1, 1, 2, 1, 3, 2, 1, 1, 1, 2, 1, 1, 1, 1, 28, 5, 2, 2484, 1, 2, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE 2*((6*1)^1) - 1 = 11 prime, so a(1)=1 2*((6*2)^1) - 1 = 23 prime, so a(2)=1 2*((6*3)^1) - 1 = 35 = 5*7 2*((6*3)^2) - 1 = 647 prime, so a(3)=2 MATHEMATICA lk[n_]:=Module[{k=1}, While[!PrimeQ[2((6n)^k)-1], k++]; k]; Array[lk, 50] (* Harvey P. Dale, Apr 02 2018 *) CROSSREFS Sequence in context: A107688 A060097 A098120 * A257462 A046876 A026584 Adjacent sequences:  A098870 A098871 A098872 * A098874 A098875 A098876 KEYWORD nonn AUTHOR Pierre CAMI, Oct 13 2004 EXTENSIONS Corrected by Harvey P. Dale, Apr 02 2018 STATUS approved

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Last modified August 21 22:56 EDT 2019. Contains 326169 sequences. (Running on oeis4.)