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A031611 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 23. 0
3389, 6938, 10897, 11317, 11530, 17021, 22669, 30154, 31909, 40289, 41498, 48761, 49645, 51437, 59005, 72353, 74513, 76154, 83569, 85306, 85889, 86474, 87061, 88241, 90026, 96829, 104413, 112397, 115085, 120557, 128410, 129125, 131282 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
cf23Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {0, 0}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len]&&cf[[(len+1)/2]] == 23]; Select[Range[132000], cf23Q] (* Harvey P. Dale, Dec 13 2019 *)
CROSSREFS
Sequence in context: A153746 A243217 A133965 * A133966 A043671 A262176
KEYWORD
nonn
AUTHOR
EXTENSIONS
First term 530 removed by Georg Fischer, Jun 16 2019
STATUS
approved

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Last modified February 25 00:32 EST 2024. Contains 370308 sequences. (Running on oeis4.)