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 A031634 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 46. 0
 4909, 26293, 26618, 44602, 65657, 66685, 91373, 120634, 153953, 154738, 156314, 157898, 193961, 238585, 281429, 283553, 286754, 289973, 332401, 333554, 334709, 335866, 338186, 341681, 344021, 345194, 387613, 395113, 400153, 447065 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..30. MATHEMATICA cf46Q[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]] == cf[[(len+1)/2]]==46]; Select[Range[500000], cf46Q] (* Harvey P. Dale, Apr 14 2020 *) CROSSREFS Sequence in context: A083607 A168028 A031834 * A250908 A179144 A036530 Adjacent sequences: A031631 A031632 A031633 * A031635 A031636 A031637 KEYWORD nonn AUTHOR David W. Wilson EXTENSIONS First term 2117 removed by Georg Fischer, Jun 16 2019 STATUS approved

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Last modified July 17 11:42 EDT 2024. Contains 374377 sequences. (Running on oeis4.)