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A031534
Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 36.
0
1298, 1318, 1346, 1358, 1362, 1366, 1382, 1394, 1398, 1438, 1442, 2919, 2949, 2964, 2973, 2991, 3057, 3063, 3081, 3093, 3102, 3117, 3153, 3171, 3174, 3189, 3207, 3237, 3246, 5188, 5204, 5212, 5228, 5244, 5252, 5260, 5276, 5284, 5300, 5308, 5324, 5340
OFFSET
1,1
MATHEMATICA
cf36Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]] == 36]; Select[ Range[6000], cf36Q] (* Harvey P. Dale, Aug 23 2019 *)
CROSSREFS
Sequence in context: A256834 A031750 A345956 * A252468 A135125 A204945
KEYWORD
nonn
STATUS
approved