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 A031421 Numbers n such that continued fraction for sqrt(n) has odd period and a pair of central terms both equal to 8. 1
 509, 1450, 2237, 2425, 3946, 4778, 5189, 5473, 5618, 5914, 6445, 6761, 7417, 8185, 9178, 9938, 10133, 10426, 10529, 10826, 10933, 11441, 11861, 12074, 12289, 12506, 12829, 13273, 14653, 14765, 15241, 16217, 16586, 16837, 17090, 17989, 18385, 18650, 18778 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 [shifted by Georg Fischer, Jun 23 2019] MATHEMATICA n = 1; t = {}; While[Length[t] < 50, n++; If[! IntegerQ[Sqrt[n]], c = ContinuedFraction[Sqrt[n]]; len = Length[c[[2]]]; If[OddQ[len] && c[[2, (len + 1)/2]] == 8 && c[[2, (len + 1)/2 - 1]] == 8, AppendTo[t, n]]]]; t (* T. D. Noe, Apr 04 2014; adapted by Georg Fischer, Jun 23 2019 *) CROSSREFS Cf. A031404-A031423. Sequence in context: A256709 A110025 A059763 * A255183 A126438 A126582 Adjacent sequences:  A031418 A031419 A031420 * A031422 A031423 A031424 KEYWORD nonn AUTHOR EXTENSIONS a(1) corrected by T. D. Noe, Apr 04 2014 Data adapted to new definition by Georg Fischer, Jun 23 2019 STATUS approved

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Last modified September 25 06:32 EDT 2020. Contains 337335 sequences. (Running on oeis4.)