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A031612
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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 24.
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0
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145, 7274, 11962, 18077, 18617, 26413, 32986, 33349, 34081, 35194, 42314, 44389, 45233, 54185, 55117, 65977, 68041, 69085, 77258, 77813, 78929, 81754, 91226, 91829, 94261, 94874, 95489, 123341, 140837, 141586, 143090, 145361, 146122, 147650
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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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cf24Q[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]] == 24]; Select[Range[150000], cf24Q] (* Harvey P. Dale, Mar 17 2016 *)
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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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STATUS
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approved
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