A020364 - OEIS

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A020364

Numbers k such that the continued fraction for sqrt(k) has period 25.

457, 881, 1049, 1181, 1189, 1306, 1585, 1594, 1754, 2125, 2797, 2906, 4121, 4157, 4234, 4253, 4330, 4442, 4469, 4517, 4913, 5077, 5597, 6418, 7442, 8249, 8345, 8570, 8689, 8825, 9593, 10145, 10301, 10498, 10625, 10673, 10889, 11401, 11930, 12053

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..40.

MATHEMATICA

cf25Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Length[ ContinuedFraction[ s][[2]]]]==25]; Select[Range[13000], cf25Q] (* Harvey P. Dale, May 05 2020 *)

CROSSREFS

Sequence in context: A325086 A215895 A142828 * A337847 A093058 A201257

Adjacent sequences: A020361 A020362 A020363 * A020365 A020366 A020367

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved