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 A031552 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 54. 0
 2918, 2942, 2946, 2962, 2966, 2974, 2978, 2994, 2998, 3022, 3046, 3058, 3062, 3086, 3106, 3118, 3126, 3134, 6564, 6573, 6591, 6609, 6621, 6636, 6663, 6693, 6702, 6717, 6729, 6753, 6771, 6774, 6789, 6801, 6807, 6852, 6861, 6879, 6924, 6933, 6951, 7017 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..42. MATHEMATICA cf54Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[s] [[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]]==54]; Select[Range[7100], cf54Q] (* Harvey P. Dale, May 13 2022 *) CROSSREFS Sequence in context: A081634 A358879 A054830 * A205253 A251353 A036260 Adjacent sequences: A031549 A031550 A031551 * A031553 A031554 A031555 KEYWORD nonn AUTHOR David W. Wilson EXTENSIONS Definition clarified by Harvey P. Dale, May 13 2022 STATUS approved

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Last modified September 22 03:20 EDT 2023. Contains 365503 sequences. (Running on oeis4.)