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A031625
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Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 37.
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0
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8861, 27970, 41737, 42557, 43385, 58733, 77509, 99514, 127097, 183713, 185429, 214994, 215921, 217781, 218714, 219649, 220586, 223409, 224354, 250729, 252733, 262873, 290285, 292441, 303341, 333890, 335045, 336202, 337361, 338522, 339685
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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cf37Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len]&&cf[[(len+1)/2]] == 37]; Select[Range[350000], cf37Q] (* Harvey P. Dale, Jun 11 2019 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Corrected and extended, and definition clarified, by Harvey P. Dale, Jun 11 2019
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STATUS
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approved
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