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 A031510 Numbers n such that continued fraction for sqrt(n) has even period and central term 12. 1
 146, 158, 162, 166, 178, 194, 327, 366, 372, 381, 393, 417, 429, 438, 580, 596, 604, 628, 636, 652, 668, 684, 692, 700, 716, 724, 740, 748, 764, 772, 780, 905, 945, 955, 995, 1005, 1030, 1055, 1070, 1195, 1205, 1220, 1302, 1338, 1434, 1578, 1614, 1626, 1758 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 MATHEMATICA epct12Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]] == 12]; Select[Range[2000], epct12Q] (* Harvey P. Dale, Jan 04 2015 *) CROSSREFS Sequence in context: A015055 A166071 A124969 * A145915 A248406 A135666 Adjacent sequences:  A031507 A031508 A031509 * A031511 A031512 A031513 KEYWORD nonn AUTHOR STATUS approved

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