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 A117522 Numbers k such that L(2*k + 1) is prime, where L(m) is a Lucas number. 15
 2, 3, 5, 6, 8, 9, 15, 18, 20, 23, 26, 30, 35, 39, 56, 156, 176, 251, 306, 308, 431, 548, 680, 2393, 2396, 2925, 3870, 4233, 5345, 6125, 6981, 7224, 9734, 17724, 18389, 22253, 25584, 28001, 40835, 44924, 47411, 70028, 74045 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For n = 24..43, we can only claim that L(2*a(n) + 1) is a probable prime. Sequence arises in a study of A269254; for detailed theory, see [Hone]. - L. Edson Jeffery, Feb 09 2018 LINKS Andrew N. W. Hone, et al., On a family of sequences related to Chebyshev polynomials, arXiv:1802.01793 [math.NT], 2018. EXAMPLE If k = 56, then L(2*k + 1) is a prime with twenty-four digits. CROSSREFS Cf. A000032, A001606, A269251, A269252, A269253, A269254. Cf. A294099, A298675, A298677, A298878, A299045, A299071, A285992, A299107, A299109, A088165, A299100, A299101, A113501. Sequence in context: A153775 A173666 A063756 * A299101 A335658 A294941 Adjacent sequences:  A117519 A117520 A117521 * A117523 A117524 A117525 KEYWORD nonn,hard AUTHOR Parthasarathy Nambi, Apr 26 2006 EXTENSIONS Values beyond 680 from L. Edson Jeffery, et al., Feb 02 2018 STATUS approved

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Last modified August 5 20:11 EDT 2021. Contains 346488 sequences. (Running on oeis4.)